76results about How to "Reduce circulation loss" patented technology

A method is provided for reducing lost circulation when aqueous, oil, or synthetic based drilling fluid is used. The method includes injecting two fluids into the well bore and lost circulation zone. The first fluid is an aqueous liquid containing at least one polymer capable of absorbing water in an alkaline environment. The aqueous liquid has a pH that inhibits at least one polymer from absorbing water. The second fluid contains a hardening composition in a base fluid having a pH sufficient to increase the pH in situ to allow at least one polymer to absorb water and expand with the absorbed water and substantially increase in size to close off the lost circulation zone and allow the hardening composition to create a plug in the well bore and set up.

A method is disclosed for reducing lost circulation in drilling wells, employing composite materials as lost circulation materials. The composites comprise a thermoplastic polymer and cellulosic fibers. Optionally the composites may include other components such as calcium carbonate, clay, oil and other blending agents.

Disclosed is a method and gellable composition for decreasing the loss of fluid during well drilling or servicing operations. The gellable composition comprises a superabsorbent polymer in an acidic aqueous liquid in which the superabsorbent is not swellable. Preferably the gellable composition also contains a viscosifier, preferably chitosan. The method is practiced by forming the gellable composition, placing it at the location of fluid loss in a well, and mixing it with a basic aqueous liquid to raise the pH and thus allow the superabsorbent to expand in volume. Advantageously, the superabsorbent, chitosan, and an acid, preferably a solid acid, preferably sulfamic acid, are admixed to form an additive for preparing the gellable composition.

A self-triggering, in-situ crosslinking fluid system is provided for controlling lost circulation for drilling in a carbonate formation. Methods of drilling a well include the steps of: (A) forming a drilling fluid comprising an aqueous phase, wherein the aqueous phase comprises: (i) water; (ii) acid, wherein the acid is at least sufficiently strong and in at least a sufficient concentration such that the aqueous phase has an initial pH of less than about 2; (iii) a viscosity-increasing agent; and (iv) a crosslinker, wherein the crosslinker is selected or controlled to crosslink the viscosity-increasing agent at a pH range anywhere in a range of about 1.5 to about 6.5 and that is at least higher than the initial pH of the aqueous phase; and (B) drilling with the drilling fluid to form a wellbore penetrating a subterranean formation.

The invention relates to an optimal current waveform controlling method for a current type two-way DC-DC convertor, and belongs to the power electronics field of the high frequency switch power source direction. According to the method, by simultaneously adjusting the duty ratio of a low voltage side and the conductive logic of two bridge arm switching tubes of a high voltage side, so that when the voltage of the low voltage side of a transformer reaches zero, a leakage inductance current of the transformer maintains the cocurrent change, the dynamic change of the leakage inductance current is completed so that the maximum peak value can be reached, when the voltage of the low voltage side of a transformer does not reach zero, the peak value of the leakage inductance current is guaranteed to be minimum under the condition of transmitting the same power. Therefore, the current-circulation loss and the conduction loss of circuits and the switching tubes and the current stress of power devices are greatly reduced, and the efficiency and performance of the circuits are improved. Meanwhile, although conducting logics of secondary side switching tubes during a boost mode and a buck mode are slightly different, the seamless switching can be achieved between the boost mode and the buck mode, so that a closed loop real-time control on the system can be easily achieved.

This invention relates to a 2-way DC convertor by phase shift of voltage regulation at one end and current stabilizing at the other plus PWM control and a control method, in which the 2-way DC converter includes a primary circuit, a switch control and a close-ring control, the primary circuit is composed of inductor L1, a switch tube S1 and serial branch 1, inductor L2, switch tube S2 and serial branch2, two auxiliary switch tubes Sa1 and Sa2, a clamp capacitor Cc and a composite branch 3, switch tubes S3 and S4 and serial branch 4, bleeder capacitor Ca and Cb, a serial branch 5 and an isolation transformer, the switch control circuit is composed of a phase shift control chip, a monostable trigger8 and a PWM control chip 9, the close ring control part is made up of a phase shift angle close ring control loop and a duty ratio close ring control loop, characterizing that: 1, suppressing the voltage peak of the tube, 2, reducing the circumfluence loss of the converter to guarantee the soft switch in the total load sphere, 3, the uncoupling control of the phase shift angle and the duty ratio realizes 2-way free flow of energies.

This invention discloses a method for blocking cracks, dissolved caverns, cavities and pores in underground rock stratum. The formula comprises: a filtering substance, a solid and a carrying fluid. The filtering substance contains multiple fluid-flowing channels that run through the filtering substance. The solid is used for blocking the fluid-flowing channels. The carrying fluid is used for carrying the filtering substance and/or the solid in the openings of cracks, dissolved caverns, cavities and pores in underground rock stratum. When the carrying fluid carrying the filtering substance into the opening, a bridge is generated to partly block the opening while still supply fluid-flowing channels. The solid and/or solidifiable fluids are introduced into the fluid-flowing channels of the filtering substance, where the solid and/or solidifiable fluid accumulate and form a sealing structure. With the formula, the openings at the wellbore section can be sealed.

The invention discloses a bidirectional hybrid bridge DC-DC converter and a half-cycle volt-second area balance control method, and belongs to a high-frequency switching power supply in the electric power and electronic field. The bidirectional hybrid bridge DC-DC converter disclosed by the invention consists of a main circuit and a control circuit; the main circuit consists of an input side, a high-frequency transformer and an output side; and the control circuit comprises a controller and a driving circuit. Based on the proposed bidirectional hybrid bridge DC-DC converter, half-cycle volt-second area balance control is adopted; the leakage inductance current effective value in a power non-transfer stage can be reduced by adjusting the duty ratio of the input side and by performing the half-cycle volt-second area balance control at the same time, and reactive current can be decreased, thereby lowering circuit on-state loss and ring current loss caused by the current; meanwhile, wide-range soft switching of each switching tube device also can be realized; and in addition, by virtue of the half-cycle volt-second area balance control, real-time control of bidirectional power flow can be realized while the complexity level of the control unit also can be lowered.

The invention discloses a current critical continuous unified control method for a bidirectional DC-DC converter, relates to a current critical continuous unified control method for a dual-active bridge bidirectional DC-DC converter, and belongs to the field of power electronics. According to the control method disclosed by the invention, voltages on a primary side and a secondary side of a transformer and a phase difference between the voltages are controlled to make the converter work in a transformer current critical continuous mode and reduce the ring current and conduction loss of the converter. In addition, a transformer current can be enabled to be in a critical continuous mode through a boundary condition and a control condition, so that the reactive loss of a circuit is reduced, the current stress of a switching tube and the ring current loss of the converter are reduced, and the efficiency and reliability of the converter can be improved. The method further can greatly lower the complexity of a control unit and realize real-time control. The method can be applied to high-frequency isolation switching power supplies.

The present application discloses a coil winding and belongs to the technical field of wireless charging. The coil winding includes an insulating layer; a first partial coil on one side of the insulating layer; and a second partial coil on the other side of the insulating layer. The first partial coil comprises a first wire section. The second partial coil comprises a second wire section. The first wire section and the second wire section each have N slots. The first wire section is divided into N+1 first sub-wires by its N slots. The second wire section is divided into N+1 second sub-wires by its N slots. The N+1 first sub-wires and the N+1 second sub-wires are electrically connected to each other one to one to form N+1 pairs of sub-wires. At least one cross structure is formed in the N+1 pairs of sub-wires. The ring current loss in the coil winding can be reduced and the wireless charging efficiency can be improved. In addition, the present application also discloses a corresponding coil module, a wireless charging transmitting device, a wireless charging receiving device, a wireless charging system, and a terminal.

The invention discloses a constant gain bidirectional DC-DC resonant converter and a control method thereof. Both sides of a transformer of the resonant converter are identical in circuit structure and include a port, two resonant capacitors and anti-parallel auxiliary diodes thereof, a resonant inductor, an auxiliary inductor and two power switch tubes. The constant gain bidirectional DC-DC resonant converter disclosed by the invention is symmetrical in circuit structure and consistent in forward and reverse working performance. Under the control method designed by the invention, the zero voltage switching (ZVS) of all power switch tubes can be well achieved with the help of the auxiliary inductor, and the circulating current loss of the converter is reduced. Meanwhile, the constant voltage gain within the range from rated load to no load is realized at the same time, thereby being capable of playing a role of power limiting in the case of overload with the help of the auxiliary diodes. The natural bidirectional flow of energy in forward and reverse operation modes is realized, and the transmission efficiency and reliability of the converter are improved.

The invention discloses a low backpressure rotary compressor. The low backpressure rotary compressor comprises a housing, a motor and a compressing mechanism; the inside of the housing is provided with a chamber; the top of the housing is provided with an air suction pipe; the motor is arranged in the chamber, and the chamber is divided into an upper chamber and a lower chamber by the motor; channels are arranged between the outer surface of the motor and the inner surface of the housing, and/or in the motor; one end of each channel is communicated with the upper chamber, and the other end of each channel is communicated with the lower chamber; the compressing mechanism is arranged under the motor, and is provided with an air suction pot. Exhaust volume of the low backpressure rotary compressor is V, flow area of the channels is S, rotating speed of the motor is F, and flow rate of air passing through the channels is v, so that v=(V*F)/S. When F<=60rad/s, 2(m/s)<=v<=25(m/s); when F>60rad/s, 8(m/s)<=v<=40(m/s). The low backpressure rotary compressor is reasonably designed, so that cooling effect is excellent, and flow resistance of air in the channels is reduced.

The invention discloses a novel AC generator stator wire rod transposition method. By use of the transposition method, 360-degree total transposition, less than 360-degree transposition, void transposition and the like can be carried out at groove portions of wire rods, parallel short circuiting on strands at the end portions of the wire rods by use of end to end joint sleeves is unnecessary, the strands in the different wire rods can be connected one by one according to a selected pitch in accordance with an "end to end correspondence" principle, each strand is wrapped by insulating varnish in advance according to requirements, and the strands can be connected at strand connecting positions by use of copper sheets equal to the sectional area of the strands. The novel stator wire rod transposition method can realize various transposition schemes of conventional strands, the circulation among the strands is substantially reduced compared to a conventional transposition scheme, and the circulation loss can be effectively reduced under the condition of different load currents. Therefore, the stator wire rod transposition method provides a reference value to a certain degree for an energy-saving design of an AC generator and has a quiet large practical significance.

The invention provides a steel coil pickling leveling unit and a steel coil production method, and relates to the technical field of steel processing. The steel coil pickling leveling unit comprises acleaning section and a leveling section which are connected with each other. The leveling section comprises a first leveling machine, and the first leveling machine comprises a knurling roller. The first leveling machine is arranged on the steel coil pickling leveling unit on line, and a separate first leveling unit does not need to be matched, so that the equipment investment and the personnel cost are reduced, the material circulation loss is reduced, and the total flow total yield is improved. Meanwhile, the thickness dimension precision error of a hot-rolled substrate can be effectively eliminated through leveling treatment, the precision requirement of a cold-rolled plate is met, and more precise use requirements of products can be met. In the process of leveling the steel, knurlingon the surface of the steel is also realized. After steel is flattened and embossed, the shape of the steel is improved, the adhesive force of zinc liquid is increased through knurling on the steel surface, a zinc layer is more stable, the thickness of the zinc layer is more uniform, and the market competitiveness of a steel plate is greatly improved.

The invention discloses a stator bar for a steam-turbine generator and an internal braided wire transposition method of the stator bar. The stator bar comprises transposed braided wires which are transversely arranged into four columns; a slot center line is taken as a boundary by the transposed braided wires on a slot part; two columns of transposed braided wires at the left side and the right side respectively form transposition groups; the transposition modes of the two transposition groups are in mirror image distribution about the slot center line; the braided wires of the two transposition groups are welded together at the end parts; and an upper layer of stator bar bodies and a lower layer of stator bar bodies in a same coil are connected with each other through a head merging sheath at the end parts of the transverse transposition groups at the same side. According to the stator bar for the steam-turbine generator and the internal braided wire transposition method of the stator bar, circulating current in the stator bar can be effectively suppressed; the circulating current loss is reduced; the operation efficiency and the operation safety of a generator are greatly improved; and the stator bar has great application value.

The application discloses a coil module, a wireless charging transmitting device, a wireless charging receiving device, a wireless charging system, and a terminal. The coil module includes a first planar coil winding and a second planar coil winding. The first turn of coil of the first planar coil winding include a first outer portion and a first inner portion, and the end portion of the first turn of coil of the first planar coil winding includes the end portion of the first outer portion and the end portion of the first inner portion. The first turn of coil of the second planar coil windingincludes a second outer portion and a second inner portion, and the end portion of the first turn of coil of the second planar coil winding includes the end portion of the second outer portion and theend portion of the second inner portion. The end portion of the first outer portion and the end portion of the second inner portion are electrically connected. The end portion of the second outer portion and the end portion of the first inner portion are electrically connected. The coil module can reduce the circulating current loss in the first planar coil winding and the second planar coil winding, and is improved in wireless charging efficiency.

The invention provides a preservative for potted flower of cymbidium faberi. It is characterized in that the preservative is essentially made from silver thiosulfate (STS). The preservative can maintain the quality of potted flower, make color more bright, and prolong the life length for various cymbidium faberi.

The invention relates to the technical field of a transformer, and particularly relates to an oil-immersed transformer low-voltage winding structure adopting transposed conductors. The oil-immersed transformer low-voltage winding structure comprises an insulting cylinder; three layers of transposed conductors are wound on the periphery of the insulating cylinder turn by turn and layer by layer, and respectively are an inner layer transposed conductor, a middle layer transposed conductor and an outer layer transposed conductor; interlayer oil passages are formed between three layers of transposed conductors; an interlayer oil passage is also formed between the inner layer transposed conductor and the outer wall of the insulating cylinder; the interlayer oil passages are axially distributed along the insulating cylinder; and end rings are mounted at both ends of each layer of transposed conductor. The oil-immersed transformer low-voltage winding structure disclosed by the invention has the advantages that eddy current loss and circulation current loss in the conductors are greatly reduced; material cost is reduced; heat dissipation efficiency is high; mechanical intensity is high; a winding process is simple; and the like.

The invention discloses a coal-fired unit peak regulation operation method, which comprises the following steps of: 1) according to the peak regulation requirement of a coal-fired unit, improving theoperation flexibility of the coal-fired unit by adopting a low-pressure cylinder steam extraction throttling auxiliary condensed water throttling mode so as to meet the variable load requirement; 2) in order to meet subsequent peak regulation requirements, supplementing the water level of a deaerator back to a normal water level, and determining the recovery rate of the water level recovery process of the deaerator according to the sustainable time of the water supplementing process; and 3) determining the peak regulation operation method of the coal-fired unit by taking the cycle loss rate xip of the peak regulation process of the coal-fired unit as an evaluation standard and taking reduction of the cycle loss rate xip as an optimization target. According to the method, the performance evaluation standard and the optimization target of the peak regulation process are provided, the circulation loss amount under the optimized operation mode is minimum, the energy loss in the peak regulation process can be reduced by reducing the circulation loss, and the energy loss is saved while it is guaranteed that the flexibility of the unit is improved. The applicability is wide, and the efficient and flexible operation of different forms of units under different load change conditions is met.

The invention discloses a scattered wire winding motor, which belongs to the technical field of motors, and is characterized in that when two stator coils are connected in series, transposition is carried out according to the inductance of parallel winding conductors, so that the inductance difference between M series conductors obtained by series connection is minimum; a wiring board is also fixed at one end where the wire outlet terminal is located, and a wiring board is located between the stator and the end cover and is in close contact with the end parts of the stator coils; the wiring board comprises a fixing ring and a plurality of wiring boxes arranged on the outer surface of the fixing ring in the circumferential direction, wiring grooves with circumferential openings are formed in the wiring boxes, and wiring copper bars are arranged in the wiring grooves; the wiring copper bars are arranged in a step shape in the axial direction; heat dissipation ribs are arranged on the circumferential outer surfaces of the wiring boxes; the M parallel-wound conductors in the stator coils are arranged according to an arrangement mode of enabling the parallel-wound conductors in the stator coils to be layered at least in the groove depth direction; and a stator notch is provided with a large arched slot wedge. According to the invention, the circulation between parallel winding conductors in the scattered wire winding motor can be effectively reduced, and the alternating current copper loss is inhibited.