Abstract:
Process and apparatus for firing a furnace using oxygen or oxygen-enriched air as the oxidant gas, comprising injection into the furnace of a plurality of oxidant jets, through nozzles, in a spaced relationship to a fuel jet, at a velocity sufficient to cause aspiration of furnace gases into the oxidant jets before the latter mix with the fuel jet, in amounts sufficient to lower flame temperature.
Abstract:
A method for minimizing the amount of nitrogen oxide pollutants produced in a process for firing a furnace using oxygen or an oxygen-enriched gas as the oxidant, in which furnace gases are aspirated into the oxidant jet prior to combustion and in which the furnace is operated using alternating low firing rate and high firing rate periods, by delaying the injection of oxidant at the high rate at the start of the high firing rate period.
Abstract:
A control system for a fractionation column which separates a feed into a heavy bottoms product, which is used as fuel for a plant, and into a light overhead product, which is used in a process, is disclosed. The fractionation column is controlled in such a manner that sufficient bottoms product is supplied to meet the plant fuel requirements while maintaining a desired distillation temperature for the overhead product. The flow rate of fuel oil to the reboiler furnace associated with the fractionation column and the flow rate of the external reflux to the fractionation column are controlled in such a manner that the objectives of supplying sufficient bottoms product to meet plant fuel requirements and supplying an overhead product having a desired distillation temperature are met while still minimizing the external reflux flow rate and the flow rate of the fuel oil to the reboiler furnace to increase fuel economy.
Abstract:
A system for operating gas discharge lamps at high frequency from a high voltage supply, typically 115 V AC with a 160 watt, 25,000 Hz output. The system provides efficient conversion, having the capability of driving any number of lamps up to maximum wattage, inherent open-cirucit and short circuit protection, and higher efficacy from the lamps. Filament power may or may not be used. Filament power is not necessary under conditions when the lamps are forced into a glow discharge to charge each cycle through the use of a tuned resonant circuit. An unsaturated inverter provides fast cut-off times. Dimming capabilities may be provided.
Abstract translation:一种用于高压供电的高压气体放电灯的系统,一般为115 V AC,160瓦,25,000 Hz输出。 该系统提供有效的转换,具有驱动任何数量的灯达到最大功率,固有的开路和短路保护以及来自灯的更高功效的能力。 灯丝功率可以使用也可以不使用。 在灯被强制进入辉光放电以通过使用调谐谐振电路为每个周期充电的条件下,灯丝功率不是必需的。 不饱和逆变器提供快速切断时间。 可以提供调光功能。
Abstract:
A method for exploring for hydrocarbons, including: simulating a seismic waveform, using a computer, wherein computations are performed on a computational grid representing a subsurface region, said computational grid using perfectly matched layer (PML) boundary conditions that use an energy dissipation operator to minimize non-physical wave reflections at grid boundaries; wherein, in the simulation, the PML boundary conditions are defined to reduce computational instabilities at a boundary by steps including, representing direction of energy propagation by a Poynting vector, and dissipating energy, with the dissipation operator, in a direction of energy propagation instead of in a phase velocity direction; and using the simulated waveform in performing full waveform inversion or reverse time migration of seismic data, and using a physical property model from the inversion or a subsurface image from the migration to explore for hydrocarbons.
Abstract:
Method for generating an effective, efficient, and stable absorbing boundary condition in finite-difference calculations, such as model-simulation of predicted seismic data. The top surface and optionally the bottom surface of the computational domain or grid are treated with one or more layers of PML (51), preferably 1D PML, assuming an orthorhombic medium in the PML implementation (52). The side surfaces are handled with one or more ABC layers (53). Further advantages may be realized by tapering earth model symmetry axis on the top and bottom of the model toward the vertical (54). The invention provides a beneficial compromise between reducing artifacts in the image or physical property model and computational efficiency and stability.
Abstract:
Method for correcting seismic simulations, RTM, and FWI for temporal dispersion due to temporal finite difference methods in which time derivatives are approximated to a specified order of approximation. Computer-simulated seismic data (51) are transformed from time domain to frequency domain (52), and then resampled using a mapping relationship that maps, in the frequency domain, to a frequency at which the time derivative exhibits no temporal dispersion (53), or to a frequency at which the time derivative exhibits a specified different order of temporal dispersion. Alternatively, measured seismic data from a field survey (61) may have temporal dispersion of a given order introduced, by a similar technique, to match the order of approximation used to generate simulated data which are to be compared to the measured data.
Abstract:
A method, including: obtaining an initial model of a subsurface property; simulating synthetic data from the initial model; obtaining recorded borehole seismic data, wherein the recorded borehole seismic data was obtained with a seismic source or receiver located in a well; and inverting, with a computer, the recorded borehole seismic data by full wavefield inversion, wherein the full wavefield inversion includes comparing the synthetic data to the recorded borehole seismic data, and computing a cost function, obtaining a gradient function from the cost function, wherein the gradient function is related to a change in the objective function with an incremental change in model parameters, using the initial model to compute an illumination function or a resolution function for seismic sources and receivers, and obtaining a conditioned gradient function by conditioning the gradient function with the illumination function or the resolution function.
Abstract:
Method and system for more efficient checkpointing strategy in cross correlating (316) a forward (328) and backward (308) propagated wave such as in migrating (326) or inverting seismic data. The checkpointing strategy includes storing in memory forward simulation data at a checkpointed time step, wherein the stored data are sufficient to do a cross correlation at that time step but not to restart the forward simulation. At other checkpoints, a greater amount of data sufficient to restart the simulation may be stored in memory (314). Methods are disclosed for finding an optimal combination, i.e. one that minimizes computation time (1132), of the two types of checkpoints for a given amount of computer memory (1004), and for locating a checkpoint at an optimal time step (306, 1214, 1310). The optimal checkpointing strategy (1002) also may optimize (1408) on use of fast (1402) vs. slow (1404) storage.
Abstract:
Method for reducing the time needed to perform geophysical inversion by using simultaneous encoded sources in the simulation steps of the inversion process. The geophysical survey data are prepared by encoding (3) a group of source gathers (1), using for each gather a different encoding signature selected from a set (2) of non-equivalent encoding signatures. Then, the encoded gathers are summed (4) by summing all traces corresponding to the same receiver from each gather, resulting in a simultaneous encoded gather. (Alternatively, the geophysical data are acquired from simultaneously encoded sources.) The simulation steps needed for inversion are then calculated using a particular assumed velocity (or other physical property) model (5) and simultaneously activated encoded sources using the same encoding scheme used on the measured data. The result is an updated physical properties model (6) that may be further updated (7) by additional iterations.