Intertwined tube coil arrangement for a delayed coker heater

A tube coil for a double fired coker heater wherein the tube coil has at least two independent flow passes in an intertwined serpentine pattern. The tubes are located in a common plane and plumbed in parallel with one another. These tube coils can be used in a number of configurations within the radiant section of a coker heater.

REFERENCE TO PENDING APPLICATIONS

This application is not based upon any pending domestic or international patent applications.

REFERENCE TO MICROFICHE APPENDIX

This application is not referenced in any microfiche appendix.

FIELD OF THE INVENTION

The present invention is generally directed towards a double fired delayed coker heater. More specifically, the present invention provides an improved tube coil layout for a delayed coker heater.

BACKGROUND OF THE INVENTION

In the petroleum refining process coker heaters are used to heat vacuum bottoms being refined in order to form gas, gas oil, and petroleum coke. One of the more common types of coker heaters is a double fired coker heater. The double fired coker heater of the prior art typically has one or more tube bundles located within the radiant section of a heater. One or more burners are located on each side of the tube coil. The burners provides the radiant heat to heat the fluid passing through the tube bundle.

The prior art tube bundles have a single flow path with tubes and fittings creating a serpentine pattern. The fluid being heated is allowed to pass through this coil while the burners provide the radiant heat source.

Oil refineries are complex facilities often times with very limited space. Over the years as a refinery is expanded, the competition for this limited space becomes ever increasing. One of the drawbacks of the prior art tube design is that it requires an excessive amount of area to locate the coker heater. Each serpentine coil arrangement contains only one process pass. This means a separate coil (line of tubes) must be added for each pass. As the number of coils increase so does the size of the coker heater and the area need to locate the coker heater.

One of the factors that complicates this situation is that the coker heater must be in relative close proximity to the coke drums. If the coker heater is located too far away from the drum the pressure drop associated with the transfer line can become excessive. Increasing the outlet pressure of the coker heater increases the rate of fouling and reduces the run length. Often times additional space is available at the refinery, however it is too far from the coke drums to be a suitable location for a coker heater.

What is needed is a tube coil design which allows for a more compact coker heater.

Hence what is needed is a coker heater and tube design which can have increased heater capacity with reduced area or footprint.

Another drawback to the prior art tube bundles is that they lead to larger coker heaters. In addition to taking up more space they are also more expensive to construct and operate.

BRIEF SUMMARY OF THE INVENTION

The present invention is a tube coil for a double fired coker heater wherein the tube coil has at least two independent flow paths configured in an intertwined serpentine pattern. The tubes are located in a common plane and plumbed in parallel with one another. These tube coils can be used in a number of configurations within the radiant section of a coker heater.

The present invention provides a tube coil arrangement with multiple passes.

Further the present invention provides a tube coil with a more dense number of passes per available area of plot space. Thus allowing for a coker heater to have a smaller footprint than the prior art.

Additionally the present invention reduces coker heater construction costs by reducing the overall size of the heater.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Turning now toFIG. 1which shows the coil configuration for a typical prior art coil20. The coil20has a single tube or flow pass with an inlet22and an outlet24.FIG. 2shows these prior art coils20located in the radiant section18of a pair of typical prior art coker heaters26. Each radiant section18has a top28, a bottom30, a pair of opposing side walls32and a pair of opposing end walls34. All of these combine to define the interior volume of the radiant section.

The coils20are located on either side of a gravity brick wall36. The gravity brick wall36is typically constructed out of refractory brick or other fire retardant materials. A plurality of burners44are located in the bottom30of the radiant section18, on either side of the coil20. The overall length of the coker heater26can vary such that the radiant surface area can be increased up to an approximate maximum tube length of 75 feet. Additional burners44can also be placed along the length of the coil20for increasing the heater capacity. The coker heater26is also provided with a convection section38and a stack40with a damper42.

When in use fluid is passed through each of the coils20. Each of these coils20is piped to be in parallel with each other such that the fluid only passes through one of the coils20. Fuel is provided to the burners44to create combustion. The radiant heat transfers into the fluid passing through the coils20. The majority of the heat entering the fluid in the radiant section18is via radiant heat transfer.

Once the fuel has been combusted in the radiant section18the heat and products of combustion rise up through the convection section38where additional transfer of heat into the fluid is achieved primarily through convective heat transfer. These hot gases eventually pass through the stack40. From there these flue gases are either further processed to reduce pollutants and/or increase heater efficiency or they are exhausted into the atmosphere. The flow rate of the flue gas and the draft inside the heater can be adjusted via the dampers42.

FIG. 3shows another prior art coker heater arrangement. This second arrangement differs from the first in that a gravity brick wall36is not employed. Once again the prior art coils20are located parallel with one another within the confines of the radiant section18. Additional coil area can be located along the same plane by increasing the length of the radiant tubes.

In this heater arrangement, a row of burners44are located along the outer sides of the coils20. A single row46of burners are located between the coils20. While the heat from the various burners can be varied, in this arrangement the center row of burners46typically burn approximately twice as much fuel than the outer row of burners44.

Turning now toFIG. 4, the coil bundle100of the present invention has two or more tubes or flow passes102intertwined with one another on a plane.FIG. 4shows the tubes102wound in a serpentine manner, however other patterns could be employed. The tubes102are located on a common plane. Each tube102has an inlet104and an outlet106.

Turning now toFIG. 5, the coils100of the present invention are shown mounted in the radiant section108of a coker heater110. When installed in the radiant section108, the tubes102are plumbed in a parallel configuration such that each tube102has its individual flow of fluid. So, the same fluid cannot pass through both tubes102of the tube coil100.

The coker heater110of the present invention has a radiant section108, a convection section112and a stack114with a damper116. The radiant section has a top118, a bottom120, a pair of opposing side walls122and a pair of opposing end walls124all of which define the interior volume of the radiant section108. A plurality of burners126are located in the bottom120of the radiant section108on either side of the coil100. Additional surface area to coils100can be located in the radiant section108. This additional surface area can be added by extending the length of the coil100.

Turning now toFIG. 6, another configuration of a coker heater110with a radiant section108, convection section112, stack114and damper116. The radiant section108has a top118, a bottom120, a pair of opposing sidewalls122and a pair of opposing end walls124two tube coils100of the present invention are installed in a radiant section108of a coker heater110separated by a gravity brick wall128. The gravity brick wall can be constructed out of refractory brick or any other fire retardant material.

At least one burner126is located on either side of the tube coils100. Additional burners126can be located along the length of the coil100. The exact number, size and location of the burners126are determined on a case by case basis dependent upon the details of the specific application.

When the present invention is in operation an individual parallel flow of fluid is pumped through tubes102of the tube coil100. The fluid enters the respective tubes through the inlet104and exits the outlet106. Radiant heat is provided by combustion of fuel in the burners126. The radiant heat passes through the tubes102and heats the fluid as the fluid passes through the tubes102.

The heat and products of combustion pass into the convection section112where convective heat transfer is used to heat the fluid passing through the tubes130located therein. The products of combustion then pass through the stack114. The flow of the products of combustion can be regulated through operation of the damper116.

The foregoing description details certain preferred embodiments of the present invention and describes the best mode contemplated. It will be appreciated, however, that changes may be made in the details of construction and the configuration of components without departing from the spirit and scope of the disclosure. Therefore, the description provided herein is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined by the following claims and the full range of equivalency to which each element thereof is entitled.