Patent Description:
Therefore, there is a need for an improved process for regulating gas streams with minimal emissions and energy loss.

<CIT> relates to variable speed power generation from industrial fluid energy sources.

<CIT> relates to a method and system for generating electricity utilizing naturally occurring gas.

<CIT> relates to wellhead pressure reduction and electrical power generation.

<CIT> relates to a system and method for generating rotational power.

The invention is in accordance with the appended claims. The present invention uses a variable-resistance power-recovery turbine to regulate, measure, and recover energy from the controlled gas stream. The power-recovery turbine can be used as a flow control element both measuring and regulating a flow. The signal from the power-recovery turbine is electronic so no transducer is needed to convert between pressure and electrical signals. Most importantly, it provides the ability to recover electrical energy from the gas flow regulating function as opposed to simply dissipating the energy as in a control valve.

In some embodiments, the power-recovery turbine can replace the control valve, eliminating any flow of fugitive emissions from the active control valve packing gland. In some embodiments, it can also replace the flow measuring device, which is typically an orifice plate with pressure sensing taps. In this situation, a single piece of equipment is inserted into a gas stream conduit instead of two. Furthermore, there are no packing glands, pressure taps, transducers on process lines, or process impulse lines, which results in greatly reduced or altogether eliminated fugitive gas emissions and much higher intrinsic safety. This results in lower maintenance costs, lower fixed emissions, and a lower risk of gas release hazards.

Energy may be recovered, preferably in the form of power, by directing a portion of the gas stream through the variable-load power-recovery turbine.

The invention may be applied in one or more processing units comprising conversion processes such as, for example, at least one of an alkylation zone, a separation zone, an isomerization zone, a catalytic reforming zone, a fluid catalytic cracking zone, a hydrocracking zone, a hydrotreating zone, a hydrogenation zone, a dehydrogenation zone, an oligomerization zone, a desulfurization zone, an alcohol to olefins zone, an alcohol to gasoline zone, an extraction zone, a distillation zone, a sour water stripping zone, a liquid phase adsorption zone, a hydrogen sulfide reduction zone, a transalkylation zone, a coking zone, and a polymerization zone processes.

In some embodiments, the process for controlling a flowrate of and recovering energy from a process stream in a processing unit comprises directing a portion of the process stream through one or more variable-resistance power-recovery turbines to control the flowrate of the process stream using a variable nozzle turbine, inlet variable guide vanes, or direct coupled variable electric load, to name a few, to vary the resistance to flow through the turbine.

The resistance to rotation of the variable-resistance turbine is varied by an external variable load electric circuit which is in a magnetic field from a magnet(s) that is rotating on the turbine. As more load is put on the circuit, there is more resistance to rotation on the turbine. This in turn imparts more pressure drop across the turbine and slows the process stream flow. An algorithm in the device calculates the actual flow through the device by measuring the turbine RPM's and the load on the circuit. The resistance to rotation can also be varied for variable position inlet guide vanes. In some embodiments, the power will be generated via power-recovery turbines with variable resistance to flow made possible by either guide vanes or variable load on the electrical power generation circuit. An algorithm to calculate actual flow using the guide vanes position, power output and RPM's can be used.

If slow control response of the turbine is an issue, then the use of the turbine is limited to slow responding or "loose" control point applications. A slow responding application is contemplated to have a response time to reach half way (i.e., <NUM>% of a difference) between a new (or target) steady state condition (e.g., temperature, pressure, flow rate) from an original (or starting) steady state condition when the new (or target) condition differs from the original (or stating) condition of at least <NUM>%, of at least one second, or even greater, for example, ten seconds, at least one minute, at least ten minutes, or an hour or more, for half of the change to completed.

The invention involves a process for controlling the flowrate of and recovering energy from a gas stream in a processing unit in accordance with claim <NUM>. The process comprises directing a portion of the gas stream through one or more variable-resistance power-recovery turbines to control the flowrate of the gas stream and generate electric power therefrom; and controlling the pressure and temperature of the gas stream so that the gas exiting the power-recovery turbine remains in the gas phase.

In some embodiments, the flowrate can be measured or controlled or both by varying one or more of the speed or shaft torque of the one or more power-recovery turbines.

The flowrate varies by less than <NUM>%, or less than <NUM>%, or less than <NUM>%. Typically, the flowrate of the gas remains constant. In some processes, changing conditions of the process, for example, catalyst deactivation in a reactor, or fouling of process equipment, over time can cause a gradual change in the desired gas flow. Moreover, many controlled process variables are indirectly controlled by flow rates, such as temperatures, pressures, or levels causing the flows to vary on a regular basis to adjust for climatic, material, or equipment performance variation cycles.

In some embodiments, the power-recovery turbine replaces a control valve in the process. In other embodiments, the power-recovery turbine is used in conjunction with a control valve, and a second portion of the gas is directed through the control valve. In some embodiments, the portion of the gas directed through the power-recovery turbine is greater than the second portion of gas directed though the control valve.

In some embodiments, the process includes receiving information from a plurality of pressure reducing devices, the plurality of pressure reducing devices comprising the one or more power-recovery turbines, or a control valve, or both; determining a power loss value or a power generated value for each of the pressure reducing devices; determining a total power loss value or a total power generated value based upon the power loss values or the power generated values from each of the pressure reducing devices; and, displaying the total power loss value or the total power generated value on at least one display screen.

In some embodiments, the method includes adjusting at least one process parameter in the processing unit based upon the total power loss value or the total power generated value. In some embodiments, after the at least one process parameter has been adjusted, an updated power loss value or an updated power generated value is determined for each of the pressure reducing devices; an updated total power loss value or an updated total power generated value is determined for the processing unit based upon the updated power loss values or the updated power generated values from each of the pressure reducing devices; and, the updated total power loss value or the updated total power generated value is displayed on at least one display screen. In some embodiments, information associated with conditions outside of the processing unit is received, and the total power loss value or the total power generated value is determined based in part upon the information associated with conditions outside of the processing unit. In some embodiments, information associated with a throughput of the processing unit is received, and the total power loss value or the total power generated value is determined based in part upon the information associated with the throughput of the processing unit. In some embodiments, the throughput of the processing unit is maintained while adjusting the at least one process parameter of the portion of a processing unit based upon the total power loss value or the total power generated value.

In some embodiments, information on the temperature and pressure of the gas stream in the processing unit is received; and at least one process parameter in the processing unit is adjusted so that the gas remains in the gas phase through the power recovery turbine. In some embodiments, at least one of the temperature, pressure, and flowrate of the gas stream is displayed on at least one display stream.

In some embodiments, the process for controlling a flowrate of and recovering energy from a gas stream in a processing unit comprises directing a portion of the gas stream through one or more variable-resistance power-recovery turbines to control the flowrate of the gas stream and generate electric power therefrom; controlling a pressure and temperature of the gas stream so that the gas exiting the power-recovery turbine remains in the gas phase; and measuring the flowrate or controlling the flowrate or both by varying one or more of the speed or shaft torque of the one or more power-recovery turbines.

The flowrate varies by less than <NUM>%, or less than <NUM>%, or less than <NUM>%. Typically, the flowrate of the gas remains constant. In some processes, catalyst deactivation over time can cause a gradual increase in variation of the gas flow.

In some embodiments, the process for controlling a flowrate of and recovering energy from a gas stream in a processing unit comprises directing a portion of the gas stream through one or more variable-resistance power-recovery turbines to control the flowrate of the gas stream and generate electric power therefrom; controlling a pressure and temperature of the gas stream so that the gas exiting the power-recovery turbine remains in the gas phase; receiving information from a plurality of pressure reducing devices, the plurality of pressure reducing devices comprising: one or more power-recovery turbines; a control valve; or, both; determining a power loss value or a power generated value for each of the pressure reducing devices; determining a total power loss value or a total power generated value based upon the power loss values or the power generated values from each of the pressure reducing devices; and displaying the total power loss value or the total power generated value on at least one display screen.

Although the following descriptions illustrate the use of the invention in several different hydroprocessing units, it is not limited to use in hydroprocessing processes. Those of skill in the art will readily recognize that it can be used in a wide variety of other processes.

<FIG> illustrates one embodiment of the process <NUM> in which a variable-resistance power recovery turbine is added to a line having a control valve on a hydrogen stream in a hydroprocessing unit. Hydrogen stream <NUM> is compressed in compressor <NUM>. The compressed hydrogen stream <NUM> is split into two portions, first and second hydrogen streams <NUM> and <NUM>. First hydrogen stream <NUM> is combined with the hydrocarbon feed stream <NUM> and sent through heat exchanger <NUM> to raise the temperature. The partially heated feed stream <NUM> is sent to fired heater <NUM> to raise the temperature of the heated feed stream <NUM> exiting the fired heater <NUM> to the desired inlet temperature for the hydroprocessing reaction zone <NUM>.

Second hydrogen stream <NUM> is sent to a power-recovery turbine <NUM> to generate power and reduce the pressure of the second hydrogen stream <NUM>. The pressure and temperature of the second hydrogen stream <NUM> are controlled so that the hydrogen remains in the gas phase as it exits from the power-recovery turbine <NUM>. As shown, control of the flowrate of second hydrogen stream <NUM> can be performed by power-recovery turbine <NUM>, the control valves <NUM>, <NUM>, <NUM>, <NUM>, or both. The flowrate of the hydrogen gas can be measured and controlled by varying the speed or shaft torque of the power-recovery turbine <NUM>.

The reduced pressure hydrogen stream <NUM> from the power-recovery turbine <NUM> is divided into four parts, hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM>. Each of the hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM> has an associated control valve <NUM>, <NUM>, <NUM>, <NUM> which can be used to control the flow of hydrogen entering the hydroprocessing bed in addition to the power-recovery turbine <NUM>, or instead of it.

As shown, hydroprocessing reaction zone <NUM> has five hydroprocessing beds <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Heated feed stream <NUM>, which contains hydrogen and hydrocarbon feed to be hydroprocessed, enters the first hydroprocessing bed <NUM> where it undergoes hydroprocessing. The effluent from the first hydroprocessing bed <NUM> is mixed with first hydrogen quench stream <NUM> to form first quenched hydroprocessed stream <NUM>.

The first quenched hydroprocessed stream <NUM> is sent to the second hydroprocessing bed <NUM> where it undergoes further hydroprocessing. The effluent from the second hydroprocessing bed <NUM> is mixed with second hydrogen quench stream <NUM> to form second quenched hydroprocessed stream <NUM>.

The second quenched hydroprocessed stream <NUM> is sent to the third hydroprocessing bed <NUM> where it undergoes further hydroprocessing. The effluent from the third hydroprocessing bed <NUM> is mixed with third hydrogen quench stream <NUM> to form third quenched hydroprocessed stream <NUM>.

The third quenched hydroprocessed stream <NUM> is sent to the fourth hydroprocessing bed <NUM> where it undergoes further hydroprocessing. The effluent from the fourth hydroprocessing bed <NUM> is mixed with fourth hydrogen quench stream <NUM> to form fourth quenched hydroprocessed stream <NUM>.

The fourth quenched hydroprocessed stream <NUM> is sent to the fifth hydroprocessing bed <NUM> where it undergoes further hydroprocessing. The effluent <NUM> from the fifth hydroprocessing bed <NUM> can be sent to various processing zones, such as heat exchange, vapor liquid flash separation, amine treating, distillation and recompression.

<FIG> illustrates another embodiment of the process <NUM> in which the combination of power-recovery turbines in parallel with control valves is used to control the flowrate of the hydrogen gas. Hydrogen stream <NUM> is compressed in compressor <NUM>. The compressed hydrogen stream <NUM> is split into first and second portions, hydrogen streams <NUM> and <NUM>. First hydrogen stream <NUM> is mixed with the hydrocarbon feed stream <NUM> and sent through heat exchanger <NUM> to raise the temperature. The partially heated feed stream <NUM> is sent to fired heater <NUM> to raise the temperature of the feed stream <NUM> exiting the fired heater <NUM> to the desired inlet temperature for the hydroprocessing reaction zone <NUM>.

Second hydrogen stream <NUM> is divided into four hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM>. Each of the hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM> has a power-recovery turbine <NUM>, <NUM>, <NUM>, <NUM> to generate power and control the flow of hydrogen entering the hydroprocessing bed as well as a control valve <NUM>, <NUM>, <NUM>, <NUM> to control the flow of hydrogen entering the hydroprocessing bed or take on the full control of the hydrogen quench stream in case of failure of the power recovery turbine.

Hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM> can be directed through either the power-recovery turbine <NUM>, <NUM>, <NUM>, <NUM>, the control valve <NUM>, <NUM>, <NUM>, <NUM>, or both. For example, a first fraction of first hydrogen quench stream <NUM> can be directed to the power-recovery turbine <NUM>, and a second fraction can be directed to the control valve <NUM>. The first fraction can vary from <NUM>% to <NUM>% and the second fraction can vary from <NUM>% to <NUM>%, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction, or <NUM>% to <NUM>% for the first fraction and <NUM>% to <NUM>% for the second fraction. The first fraction sent to the power-recovery turbine will typically be greater than the second fraction sent to the control valve. Thus, the flow of the hydrogen quench streams <NUM>, <NUM>, <NUM>, <NUM> can be controlled by the power-recovery turbines <NUM>, <NUM>, <NUM>, <NUM>, the control valves <NUM>, <NUM>, <NUM>, <NUM>, or both, allowing excellent process flexibility. This arrangement allows for constant power turbines that do not control flow where the flow through the turbines is set at some level and the control is actually done with the parallel trim control valve. Alternatively, a flow controlling turbine could take all the flow and the parallel control valve just remain in standby mode to take over control in case of any turbine malfunction wherein the turbine needs to be bypassed. This arrangement is more likely to appear in redesigns of existing plants as the control valves are already in place and their addition involves little installation cost.

As shown, hydroprocessing reaction zone <NUM> has five hydroprocessing beds <NUM>, <NUM>, <NUM>, <NUM>, and <NUM>. Feed stream <NUM>, which contains hydrogen and hydrocarbon feed to be hydroprocessed, enters the first hydroprocessing bed <NUM> where it undergoes hydroprocessing. The effluent from the first hydroprocessing bed <NUM> is mixed with first hydrogen quench stream <NUM> to form first quenched hydroprocessed stream <NUM>.

The fourth quenched hydroprocessed stream <NUM> is sent to the fifth hydroprocessing bed <NUM> where it undergoes further hydroprocessing. The effluent <NUM> from the fifth hydroprocessing bed <NUM> can be sent to various processing zones, as described above.

The process of <FIG> is similar to that of <FIG>, except that the control valves <NUM>, <NUM>, <NUM>, <NUM> are not present. In this arrangement, the flowrate of second hydrogen stream <NUM> is controlled by power-recovery turbines <NUM>, <NUM>, <NUM>, <NUM>. This arrangement is more likely to appear in new plant designs than in redesigns of existing plants.

The devices and processes of the present invention are contemplated as being utilized in a hydroprocessing reaction zone. As is known, such hydroprocessing reaction zones utilize a process control system, typically on a computer in a control center.

The process control system described in connection with the embodiments disclosed herein may be implemented or performed on the computer with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, or, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be a combination of computing devices, e.g., a combination of a DSP and a microprocessor, two or more microprocessors, or any other combination of the foregoing.

The steps of the processes associated with the process control system may be embodied in an algorithm contained directly in hardware, in a software module executed by a processor, or in a combination of the two. An exemplary storage medium is in communication with the processor such the processor reads information from, and writes information to, the storage medium. This includes the storage medium being integral to or with the processor. Alternatively, the processor and the storage medium may reside as discrete components in a user terminal. These devices are merely intended to be exemplary, non-limiting examples of a computer readable storage medium. The processor and storage medium or memory are also typically in communication with hardware (e.g., ports, interfaces, antennas, amplifiers, signal processors, etc.) that allow for wired or wireless communication between different components, computers processors, or the like, such as between the input channel, a processor of the control logic, the output channels within the control system and the operator station in the control center.

In communication relative to computers and processors refers to the ability to transmit and receive information or data. The transmission of the data or information can be a wireless transmission (for example by Wi-Fi or Bluetooth) or a wired transmission (for example using an Ethernet RJ45 cable or an USB cable). For a wireless transmission, a wireless transceiver (for example a Wi-Fi transceiver) is in communication with each processor or computer. The transmission can be performed automatically, at the request of the computers, in response to a request from a computer, or in other ways. Data can be pushed, pulled, fetched, etc., in any combination, or transmitted and received in any other manner.

According to the present invention, therefore, it is contemplated that the process control system receives information from the power-recovery turbine <NUM> or <NUM>, <NUM>, <NUM>, <NUM> relative to an amount of electricity generated by the power-recovery turbine <NUM> or <NUM>, <NUM>, <NUM>, <NUM>. It is contemplated that the power-recovery turbine <NUM> or <NUM>, <NUM>, <NUM>, <NUM> determines (via the processor) the amount of electricity it has generated. Alternatively, the process control system receiving the information determines the amount of electricity that has been generated by the power-recovery turbine <NUM> or <NUM>, <NUM>, <NUM>, <NUM>. In either configuration, the amount of the electricity generated by the power-recovery turbine <NUM> or <NUM>, <NUM>, <NUM>, <NUM> is displayed on at least one display screen associated with the computer in the control center. If the hydroprocessing reaction zone comprises a plurality of power-recovery turbines <NUM>, <NUM>, <NUM>, <NUM>, it is further contemplated that the process control system receives information associated with the amount of electricity generated by each of the power-recovery turbines <NUM>, <NUM>, <NUM>, <NUM>. The process control system determines a total electrical power generated based upon the information associated with the each of the power-recovery turbines <NUM>, <NUM>, <NUM>, <NUM> and displays that the total electrical power generated on the display screen. The total electrical power generated may be displayed instead of, or in conjunction with, the amount of electrical power generated by the individual power-recovery turbines <NUM> or <NUM>, <NUM>, <NUM>, <NUM>.

As discussed above, the electrical energy recovered by the power-recovery turbines <NUM> or <NUM>, <NUM>, <NUM>, <NUM> is often a result of removing energy from the streams that was added to the streams in the hydroprocessing reaction zone. Thus, it is contemplated that the processes according to the present invention provide for the various processing conditions associated with the processing reaction zone to be adjusted into order to lower the energy added to the steam(s). The hydrogen leaving the hydrogen compression section is compressed to a pressure so that the flow can be controlled to the higher pressure reactor combined feed heat exchangers and the feed furnace and first reaction bed in addition to each hydrogen stream between beds. The turbine power recoveries between beds may signal on opportunity to decrease the compressor outlet pressure while still maintaining the flow control as the energy recovered from the power-recovery turbines is set above the experientially determined economically optimum amount. In this way the turbines can signal an opportunity to save even more energy than recovering it in the turbine but instead never add a portion of that energy to the system in the first place.

It is contemplated that the process control system receives information associated with the throughput of the hydroprocessing reaction zone, and determines a target electrical power generated value for the turbine(s) since the electricity represents energy that is typically added to the overall hydroprocessing reaction zone. The determination of the target electrical power generated value may be done when the electricity is at or near a predetermined level. In other words, if the amount of electricity produced meets or exceeds a predetermined level, the process control system can determine one or more processing conditions to adjust and lower the amount of electricity generated until it reaches the target electrical power generated value.

Thus, the process control system will analyze one or more changes to the various processing conditions associated with the hydroprocessing reaction zone to lower the amount of energy recovered by the power-recovery turbines of the hydroprocessing reaction zone. Preferably, the processing conditions are adjusted without adjusting the throughput of the hydro processing zone. This allows for the hydroprocessing reaction zone to have the same throughput, but with a lower operating cost associated with the same throughput. The process control software may calculate and display the difference between the target electrical power generated value and the total electrical power generated on the display screen.

For example, the process control software may recognize that the total electrical power generated exceeds a predetermined level. Accordingly, the process control software may determine the target electrical power generated value. Based upon other data and information received from other sensors and data collection devices typically associated with the hydroprocessing reaction zone, the process control software may determine that the amount of fuel consumed in the heater can be lowered. While maintaining the throughput of the hydroprocessing reaction zone, the amount of fuel consumed in the heater is lowered. While this may lower the electricity generated by the power-recovery turbine, the lower fuel consumption provides a lower operating cost for the same throughput. It may also determine that reduced pressure or flow is optimal for the throughput of the hydrogen compressors. It this way steam or electricity to the compressor driver could be decreased.

Thus, not only does the present invention convert energy that is typically lost into a form that is used elsewhere in the hydroprocessing reaction zone, the hydroprocessing reaction zones are provided with opportunities to lower the energy input associated with the overall hydroprocessing reaction zone and increase profits by utilizing more energy efficient processes.

It should be appreciated and understood by those of ordinary skill in the art that various other components, such as valves, pumps, filters, coolers, etc., are not shown in the drawings as it is believed that the specifics of same are well within the knowledge of those of ordinary skill in the art and a description of same is not necessary for practicing or understanding the embodiments of the present invention.

While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.

Claim 1:
A process for controlling a flowrate of and recovering energy from a gas stream in a processing unit comprising:
directing at least a portion of the gas stream (<NUM>) through one or more variable-resistance power-recovery turbines (<NUM>) to control the flowrate of the gas stream (<NUM>) and generate electric power therefrom; and
controlling a pressure and temperature of the gas stream (<NUM>) so that the gas exiting the power-recovery turbine (<NUM>) remains in a gas phase;
wherein the flowrate varies by less than <NUM>%; and
wherein the resistance to rotation of the one or more variable-resistance turbines (<NUM>) is varied by an external variable load electric circuit which is in a magnetic field from a magnet that is rotating on the turbine, and wherein an algorithm in the one or more variable-resistance power-recovery turbines (<NUM>) calculates the actual flow through the device by measuring the turbine RPM's and the load on the circuit.