Self-Contained Mobile Dispensing System for In Situ Re-insulation

FIELD OF INVENTION

The present invention relates generally to a mobile pumping system and more particularly to a mobile pumping system for dispensing piping insulation

material.

BACKGROUND OF THE INVENTION

In established regions or municipalities, particularly those that are densely populated, underground pipes carry steam, hot water, or other heat and

energy source materials, to commercial, industrial, and residential buildings. In order to reduce heat dissipation through these mostly metallic pipes, pipes

are typically insulated during installation. However, due to shortcomings in

design or workmanship, or damage from environmental elements or aging, some

of the original insulation systems fail as effective barriers to heat loss.

Generally, the design of regional or municipal underground piping uses

metal pipes laid inside concrete or tile conduits of a greater diameter than the pipes resulting in an annular space there between. Before the pipe is laid into

the ground, insulating material, such as foamed plastic, is provided around the pipe filling this annular space. However, with time, this insulating material

deteriorates and heat losses increase.

U.S. Patent No. 5,732,742, entitled "Method for re-insulating installed steam pipe in situ," assigned to the same assignee as the instant invention and

hereby incorporated herein by reference in its entirety, teaches repairing this deteriorated insulation by injecting plastic foam insulation (polyisocyanurate

foam) into the annular space. The process for re-insulating underground steam

pipe in situ first involves creating at least one hole in a suitable location in the ground and inserting a liner into the hole. Then, using any suitable tool such as

a drill, torch or jack hammer, a hole is opened into the conduit to allow insertion

of a tubing through the conduit (through the liner). A first end of the tubing is

positioned through the hold and proximate to the pipe and a second end of the

tubing is attached to a pumping system. The foam is then pumped through the

tubing around the pipe. Once the tubing is removed and the foam is allowed to

cure it becomes a rigid insulation for the pipe.

Industrial application of the re-insulating process typically uses a closed

cell, high temperature, plastic foam insulation (polyisocyanurate foam) as a means of re-insulating the underground lines. This process, also known as

"Condufill™ ", uses a high temperature Teflon hose to apply the insulating foam through a vacuum, excavation or a manhole. Such process, however, requires a

dispensing system with a suitable metering device to supply the materials which make up the insulating foam to the injection hoses for application to the

conduit air spaces.

SUMMARY OF THE INVENTION

The present invention addresses, among others, the need for delivering

through an injection hose a well blended mixture of chemical reactants, at the proper flow rate and temperature, for in situ application of the polyisocyanurate insulation to existing pipe systems.

In accordance with the purpose of the present invention a self contained, mobile system is provided with a suitable metering pump capable of delivering

a well blended mixture of the chemical reactants through an injection hose of up to 80 feet from the mix head. The metering pump provides the mixture at a

combined flow rate that is suitable for the required hose length and varying temperature conditions. For example, the metering pump is capable of

providing a combined flow rate averaging 50 pounds a minute for a particular

injection hose length and temperature. The mobile system carries a significant

quantity of reactant products and maintains them at temperatures that yield the reaction mixture at a given conversion when it exits the injection hose.

In a typical implementation of the mobile system, it is configured as a

self-contained, mobile foam dispensing system, wherein the foam is formed by

mixing several reactants. In addition to the metering pump, the mobile system includes a generator that provides power to the overall system. For each

reactant, a holding tank is provided for storing the reactant along with a chiller

unit for chilling the reactant and a heating unit for heating the reactant. A mix

head nozzle is provided in the mobile system for mixing the reactants. The mix

head nozzle has an elongated straight cylindrical shape and includes a plurality

of orifices oriented to allow mixing of the reactants in a dispensing mode of

operation. The metering pump controls and supplies the reactants to the mix

head nozzle, in stoichiometric proportions and at predetermined temperature

and pressure. The system additionally includes a hose connecting the mixing

tank to the mix head nozzle. The mix head nozzle is secured to the hose, and its elongated shape allows a better fit to the hose and room for more than one clamp for securing it to the hose. This configuration minimizes the risk of the

hose coming off the nozzle during dispensing mode.

In one embodiment, the mobile system also includes bypass valves that

permit high speed circulation of the constituent reactants without passing through the mix head nozzle. By circulating through the bypass valves, the

reactants avoid friction induced heating.

In yet another embodiment, in-line temperature probes and console

readouts are additionally provided in one or more locations throughout the mobile system. These in-line probes and readouts are provided for temperature monitoring of the constituent and mixed reactants.

In yet another embodiment, the system further includes agitators. The

agitators are provided along with the holding tanks and heaters for preheating

the reactants in a uniform way and for reducing fluctuations in temperature

during dispensing mode.

In yet another embodiment, a self sufficient mobile system is used to

perform a method for dispensing materials in situ. The method involves

pressurizing one or more chemical ingredients, including passing the chemical

ingredients through a respective metering pump. To achieve a mixing temperature, the chemical ingredients are heated and cooled, including by re

circulating them through a heat exchanger that interfaces with heater and

cooler units. The method further involves passing the chemicals through a mix

head nozzle that receives the chemical ingredients as separate flows and, for

more than one chemical ingredient, combines them to form the insulation material. Again, the metering pump is operative to supply each of the chemical

ingredients to the mix head nozzle in stoichiometric proportions and at

predetermined temperature and pressure. The material is then dispensed in

situ through a hose.

As can be further appreciated, being self-contained and mobile, the system is more efficient and easy to use compared to prior art systems. With

this system, set up and disassembly are not required each time it is brought to a

new location. Moreover, the mobile system is more easily maneuverable as the

metering components, including the generator and compressor, are contained in

it and there is no need to tow them separately.

These and other features, aspects and advantages of the present invention will become better understood from the description herein, appended

claims, and accompanying drawings as hereafter described.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings which, are incorporated in and constitute a

part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. Wherever convenient, the same reference numbers will be used throughout the

drawings to refer to the same or like elements.

FIG. I illustrates the functional subsystems of a mobile pumping system.

FIG. 2 illustrates the flow path for a reactant through the flow control

sub system. FIG. 3 illustrates the flow path for a reactant through the temperature

control sub

FIG. 4 illustrates the mobile system with a. mixing sub system in more

detail.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention addresses the aforementioned needs associated

with application of insulation to underground piping. As mentioned,

underground piping require repairs to maintain their effectiveness as barriers to energy loss. Accordingly, a self-contained, mobile system is provided with a suitable metering pump capable of delivering a well blended mixture of the

chemical reactants through an injection hose. With this metering pump, the

combined flow rate of the reactants varies based on hose lengths and

temperatures, averaging 50 pounds per minute, with dispensing from a hose of up to 80 feet in length. The mobile system is powered by a generator.

The mobile system carries a significant quantity of reactant materials

and maintains them at temperatures that yield a proper mixture at a given

conversion when the mixture exits the injection hose. For temperature control, the mobile system includes for each reactant a holding tank for storing the reactant, along with a chiller unit for chilling the reactant, and a heating unit

for heating the reactant. Preferably, the mobile system further includes

agitators for improving the uniformity of the reactant heating and cooling. To

monitor the constituent reactants and mixture in the mobile system, it is

configured with one or more in line probes and console readouts. For mixing the reactants, the mobile system is equipped with a mix head nozzle. The mix

head nozzle has an elongated straight cylindrical shape and includes a plurality

of orifices oriented to allow mixing of the reactants in a dispensing mode of operation. The metering pump controls and supplies the reactants to the mix

head nozzle, in stoichiometric proportions and at a predetermined temperature and pressure. To supply the mixture in situ, the mobile system additionally

includes a hose connecting the mixing tank to the mix head nozzle. The mix

head nozzle is secured to the hose, and its, elongated shape allows a better fit to

the hose and room for more than one clamp for securing it to the hose. This configuration minimizes the risk of the hose coming off the nozzle during dispensing mode.

FIG. 1 shows the functional sub systems of a mobile pumping system.

Functionally, this system 100 includes a flow control sub system 102, a temperature control subsystem 104 and a chemical mixing sub system 106. In

this exemplar configuration, the reactants (constituent chemical components of the plastic foam insulation) flow separately as they enter into the flow control

sub system 102. Each of the three reactants is transferred from a container, e.g., a 55 gallon drum, to a separate holding tank, using a reciprocating drum

pump. In one configuration the combined capacity of the three holding tanks exceeds 2400 pounds, which provides for storage of chemicals sufficient to fill 200-500 feet of conduit depending on the size of the annular space between the

conduit and pipe. Each of the reactants is expected to reach a desired pressure

and temperature before the mixing stage as it flows through the system 100. Accordingly, the reactants are pumped out of the flow control sub system 102 at

the proper pressure and in the proper stoichiometric proportions. As they are

pumped out, the reactants circulate through the temperature control sub system 104 until they achieve the desired mixing temperature. Then, the

reactants are mixed in the mixing sub system 106 and the resulting foam is

applied in situ to the pipe 108.

As they circulate, the reactants pass through in-line heaters which heat

them. In some instances, the external areas of each of the holding tanks are

fitted with band heaters to expedite the heating of the reactants when required. Furthermore, an agitator is added to each holding tank 204 to provide a more

uniform temperature distribution of the reactant within the tank.

In one embodiment, bypass valves are installed to provide high speed

circulation of the reactants without passing through the mix head 106 and

gaining friction heat. This process allows the reactant chemicals at each location, (the pumps, hoses and fittings) to acquire a stabilized temperature,

which reduces fluctuations, during the dispensing mode.

FIG. 2 depicts the flow path for a constituent chemical within the flow

control subsystem 102. The flow control sub system 102 includes separate

holding tanks 204, filters 206, check ball assembly valves 208, and metering pumps 210 for each of the constituent chemicals. Each of the constituent chemicals is kept isolated from the others throughout its flow within the system

100, until it reaches the mixing sub system (106 in FIG. 1). Thus, from the flow

control sub system 102, the flow paths for this and each of other chemical constituents (reactants) continue separately until they reach the mixing sub

system 106.

As further illustrated, each of the chemical constituents of the insulating

foam is initially held in a separate 55 gallon drum 200, and from there it is

transferred to a separate chemical holding tank 204, using reciprocating drum pump 202. In this instance, each holding tank is pressurized using a blanket of

dry air pumped on top of the chemical The resulting pressure of approximately

40-50 psig is maintained by the air blanket for as long as the mobile pumping

system is operating. The air pressure in each holding tank forces the respective reactant out of its holding tank 204. And, as each reactant traverses the system

separately before it reaches the mixing subsystem (106, FIG. 1), it is pushed

through respective screen filters 206 and the check valve (ball assembly valve) 208 into a respective low pressure side of the metering pump 210. The metering

pump 210 controls the respective flow of each reactant out of the flow control sub system 102 and into the temperature control sub system 104.

FIG. 3 depicts the flow path for each reactant through the temperature control sub system 104. Each separate reactant path within the temperature

control sub system includes a heat exchanger (e.g., shell and tube heat

exchanger) 302, a temperature probe (thermocouple) 304, and a control

(diversion recirculation) valve 310. The chiller 308 and heater 306 operate to

directly or indirectly heat or cool each of the reactants as they flow through the respective heat exchanger 302. For example, a reactant passing through the

respective heat exchanger 302, is heated and cooled indirectly by a heat transfer fluid such as a water glycol solution that is, in turn, heated by the heater 306 or

cooled by the chiller 308. The heat transfer fluid flows through one side of a

shell and tube heat exchanger as the reactant flows on the other side.

The temperature probe 304 monitors the temperature of each reactant as it flows out of its respective heat exchanger 302. The reactants are respectively

heated and cooled to the ideal temperature for mixing. Feedback from each

temperature probe 304 is directed to a control center 312, where based on the temperature reading for each reactant, an operator can open or close a valve controlling the heat transfer fluid flow from the heater 306 or heat transfer

fluid flow from chiller 308.

Additionally, until the ideal mixing temperature is achieved, the operator

controls the diversion recirculation valve 310 for directing the reactants into a

recirculation loop. Once the ideal mixing temperature is achieved, the recirculation diversion valve 310 is closed and each of the constituent reactants

flows to the mixing sub system 106.

In one implementation, one or more in-line temperature probes and console readouts for the temperature probes 310 are installed in one or more

locations through the mobile system. In particular, to further monitor

temperature levels of the reactant, temperature probes and readouts are

installed at the supply strainer locations and just prior to the entrance to the

mix head (mixing subsystem 106). By providing more accurate temperature

readings of the reactant chemicals throughout the recirculation mode, the operator can monitor the quality of the heating and cooling processes as the

mobile system is started and brought up to the proper state of operation.

For allowing the operator to utilize more of the preheated and prepared chemicals for dispensing, low level bypass switches are installed on the holding

tanks. This allows the operator to bypass automatic shut off valves intended to

prevent extraction of the reactants from the holding tanks when they reach a level of 15% or less.

At the final stage of their flow, the reactants are combined in the mixture sub system 106 to produce the foam insulation. FIG. 4 shows the mobile system with more details of the mixing sub system 106 in which the reactants 402 are

combined to form the insulating foam 410. The mixing sub system 106 includes a mix head with three small diameter orifices 404 oriented in such a way that

the flow through each will hit the flow of the other two when in the dispense

mode.

In the recirculation mode, there is a cleanout plunger 408 simultaneously blocking the path from one orifice to the other and allowing the chemicals to

flow through a recirculation port (not shown). In operation, once the start

button is pressed, and the pressure build timer expires, the cleanout plunger

opens, blocking the recirculation ports while opening the mixing chamber. This allows the three chemicals 402 to contact each other in the center of the mixing

chamber at a very high velocity, due to the small hole in the orifices 404. This

is called impingement mixing and it ensures that the three separate chemicals

are thoroughly mixed. Preferably, as shown, the mix head is mounted to the truck wall at a

higher location to allow the operator a clearer view of the areas for the

calibration of the unit while pumping. This helps reduce over pressurization

and lost mix head shots when pumping. The higher location also makes service of the needles and orifices on the mix head quicker and easier.

Preferably also, the mix head nozzle of the unit 106 is modified from the

standard, tapered design to a straight milled and lengthened nozzle. This design allows the hose to fit better and creates more room for the dual securing

clamps 406. A better and more secure fit reduces the risk of the hose separating from the nozzle during the dispensing mode.

In addition to these improvements, one embodiment of the mobile system further includes an outside fan unit to help displace heat from the generator

and push cooler air through the chiller. This improves cooling time of the

reactants.

In yet another embodiment, quieter, muffled and smaller generators are

used in place of PTO (power take off) and hydraulic generators as power sources for the electrical panel of the mobile system. This saves space within the box of

the truck, reduces overall weight of the vehicle, and reduces wear and tear on

the engine when the PTO runs.

In sum, although the present invention has been described in considerable detail with reference to certain preferred versions thereof, other

versions are possible. Therefore, the spirit and scope of the appended claims is

not limited to the description of the preferred versions herein.