Patent Application
20140202192
In order to shorten downtime for turnarounds, refineries use cold nitrogen injected into reactor recycle loops to cool down reactors quicker than with simply using the hydrocarbons in the system. This system will reduce the amount of nitrogen required for most cooldown cycles by almost ⅔-increasing the value to the customer drastically.
Systems outfitted with piping of incompatible metallurgy are not able to use liquid nitrogen and the nitrogen must be vaporized and brought to a acceptable temperature before injecting into the customer's system (using mobile nitrogen vaporization units). Systems outfitted with stainless steel piping are able to inject liquid nitrogen directly, which requires far less nitrogen—usually around ⅓, but the majority of cool downs are with cold gas. Both technologies are mature, although direct injection generally requires a higher level of safety consciousness. Some customers with stainless piping are further reluctant to pursue liquid cooldowns because of the risk of recycle compressor failure, or other failures that could result in liquid nitrogen reaching the reactor itself. The major drawback of cold gas systems is that the time it takes to perform the cool down to the customer's satisfaction, and the nitrogen usage—both of which offer an opportunity to create value for the customer through novel solutions.
A reactor liquid cool down apparatus includes; a compressor comprising an inlet and an outlet, a first conduit connecting a reactor outlet to the compressor inlet, a mixing zone, comprising an inlet, an outlet, and a liquid cryogen inlet, a first control valve, a second conduit connecting the compressor outlet and the first control valve, a third conduit connecting the first control valve to the mixing zone inlet, a temperature control valve, a fourth conduit connecting the temperature control valve with the liquid cryogen inlet, a means for monitoring a mean fluid temperature within the second conduit, a second control valve, wherein the first control valve and the second control valve are configured to isolate the mixing zone, a fifth conduit connecting the second control valve with the mixing zone outlet, a sixth conduit connecting the second control valve to a reactor inlet, a bypass control valve.
Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The proposed solution may include a stainless piping skid that may be mounted on a non-DOT trailer (capable of being pulled by non-DOT pickup trucks). The customer's entire recycle stream is redirected through temporary piping into the skid, where liquid nitrogen could be injected without risk to the customer's piping.
The skid would include automatic bypass and isolation valves as well as a temperature control valve and multiple thermocouples (for voting purposes). The customer's stream would enter the skid through the first isolation valve. After a sufficient length of pipe to ensure adequate mixing, the combined stream would pass over three thermocouples before exiting the skid through the second isolation valve back Into the customer's piping.
The thermocouples would be used to isolate and bypass the skid in the event a predetermined low temperature limit was reached (to be agreed upon with the customer—2 out of 3 voting). The liquid nitrogen would enter the piping via a temperature control valve—the thermocouples would also be used as the control point (also to be agreed upon with the customer). Liquid nitrogen pressure would be provided by a small mobile nitrogen pumping and vaporization unit or simply the centrifugal pump on the liquid nitrogen transport. The skid would be controlled by a simple PLC. Power and air would be provided by the transport or pumper. In this manner, customers with incompatible piping in their existing system would be able to enjoy the benefits of liquid cool down.
Turning to
Compressor outlet 106 is connected to second conduit 112, which is then connected to first control valve 111. First control valve 111 is connected to third conduit 113 which is connected to the inlet 108 to mixing zone 107. Mixing zone 107 may be made of stainless steel.
Temperature control valve 115 is connected to fourth conduit 115, which is then connected to the cryogenic inlet line 110 of mixing zone 107. The outlet 109 of mixing zone 107 is connected to conduit 118, which is then connected to second control valve 117. Second control valve 117 is then connected to fifth conduit 118, which is then connected to inlet 102 of reactor 101.
Temperature control valve 114 is connected to fourth conduit 115 which is then connected to liquid cryogen inlet 110. The liquid cryogen may be liquid nitrogen.
If the mixing zone 107 must be bypassed, first control valve 111, temperature control valve 114 and second control valve 117 may be closed, and bypass valve 119 may be opened.
A reactor liquid cool down apparatus, comprising;
The reactor liquid cool down apparatus, wherein the mixing zone (107) is stainless steel.
This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/755,117 filed on Jan. 22, 2013, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61755117 | Jan 2013 | US |
