533 results about "Heat torch" patented technology

The invention features a replaceable cartridge for a plasma arc torch. The cartridge includes a cartridge body having a first section and a second section. The first and second sections are joined at an interface to form a substantially hollow chamber. The interface provides a coupling force that secures the first and second sections together. The cartridge also includes an arc constricting member located in the second section; an electrode included within the substantially hollow chamber; and a contact start spring element affixed to the electrode. The spring element imparts a separating force that biases the electrode toward at least one of the first section or the second section of the body. The separating force has a magnitude that is less than a magnitude of the coupling force.

Systems and methods of the present disclosure includes a mixer configured to mix air and hydrocarbons and a burner configured to receive the mixed air and hydrocarbons and to generate syngas. The system also includes a cooling system configured to receive the syngas and to cool the syngas to form cooled syngas. The system further includes a collector configured to collect carbon from the cooled syngas as soot. Moreover, the system includes a flare stack configured to receive the cooled syngas and to burn off at least part of the cooled syngas.

The invention discloses a remote ignition control system for a release flare, and relates to the technical field of release flare control, the system comprises the following components: a fault detection module, a fault isolation module, a standby module, a redundant circuit switching module, a fault diagnosis module and a wireless communication module; by integrating multiple modules of fault detection, fault isolation, standby module and redundant circuit switching, fault diagnosis and wireless communication, comprehensive remote monitoring and management of the release flare ignition control system are achieved, when the system detects a fault, electrical connection of a fault component can be rapidly cut off, and the safety of the release flare ignition control system is improved. And the standby module or the redundant circuit is automatically switched, so that the continuous and stable operation of the system is ensured, the reliability and the safety of the system are remarkably improved, and the risk of production interruption caused by faults is reduced.

This flame-retardant resin composition comprises a thermosetting resin and a flame-retarding agent, and has a ΔEr value of 30 or less as determined by the following procedure. Procedure: (i) A test plate (size: 120 mm square, 2 mm in thickness) under the conditions including a mold temperature of 175°C and a curing time of 3 minutes is prepared using the flame-retardant resin composition. (ii) A torch burner (30 mm with respect to a flame length of about 100 mm) is set to the center of one surface of the vertically-set test plate such that the angle with respect to the test plate becomes 90°, and a flame from the torch burner is applied to the center for 5 minutes. (iii) For the center of the other surface of the test plate and two points which are located on a straight line passing through the center of the other surface of the test plate and are each 3 mm away from this center, color differences between before and after the contact with the flame are separately measured and an average value (ΔEr) is determined.

The utility model relates to the technical field of combustion torches, in particular to an internal combustion type biogas torch. Comprising a base, the upper surface of the base is fixedly connected with a torch cylinder and an automatic ignition system, the torch cylinder is arranged on the outer side of the automatic ignition system in a sleeving mode, one side of the torch cylinder is fixedly connected with an air inlet pipe, one end of the air inlet pipe is fixedly connected with the automatic ignition system, and the middle section of the air inlet pipe is provided with a dehumidification mechanism. When marsh gas is injected into the torch barrel through the gas inlet pipe for combustion, the cooling-water machine is started to cool the wall of the U-shaped pipe, and when the marsh gas in the water inlet pipe flows through the surface of the U-shaped pipe, water vapor in the marsh gas is condensed on the wall of the U-shaped pipe, so that the water vapor in the marsh gas is filtered out, and the combustion efficiency of the marsh gas is improved; meanwhile, after biogas is introduced into the gas inlet pipe, the U-shaped pipe vibrates in multiple directions, condensate water on the surface of the U-shaped pipe is vibrated to fall into the water tank, and the situation that the residual condensate water on the surface of the U-shaped pipe evaporates again, and water vapor is mixed into the biogas again is avoided.

The utility model discloses a black water waste heat high-quality recycling system which comprises a high-pressure purification flash evaporator, a low-pressure purification flash evaporator, a high-flash tank and a low-flash tank, black water is sequentially subjected to four times of flash evaporation stripping, flash steam generated by the high-pressure purification flash evaporator and flash steam generated by the low-pressure purification flash evaporator respectively act with an evaporator to generate saturated steam, and the saturated steam is separated from the low-flash tank. The saturated steam can meet different process applications after being pressurized by the steam pressurizing device; the high-flash condenser is used for condensing high-flash steam discharged by the high-flash tank, non-condensable gas enters a torch treatment pipeline, and condensed water is recycled in the process; the low flash tank is used for receiving the liquid part discharged by the high flash tank; the low-flash condenser is used for condensing low-flash steam in the low-flash tank and then returning the condensed low-flash steam to a process system for recycling; and the demineralized water preheater is used for receiving part of the low-flash liquid discharged by the low-flash tank to preheat the demineralized water. According to the utility model, the waste heat of black water can be extracted in a grading manner and efficiently utilized.

Systems and methods of the present disclosure includes a mixer configured to mix air and hydrocarbons and a burner configured to receive the mixed air and hydrocarbons and to generate syngas. The system also includes a cooling system configured to receive the syngas and to cool the syngas to form cooled syngas. The system further includes a collector configured to collect carbon from the cooled syngas as soot. Moreover, the system includes a flare stack configured to receive the cooled syngas and to burn off at least part of the cooled syngas.

The invention discloses a rotary kiln pyrolysis process preheating and replacing method which comprises the following steps: replacing and preheating an upgrading system when a rotary kiln is started, performing low-load operation on the rotary kiln, heating the rotary kiln by a rotary kiln hot blast stove and a flue gas fan, closing a pipeline valve from a dry gas fan to a first dust remover, and performing low-load operation on the rotary kiln; a rotary kiln nitrogen replacement valve is slightly opened, nitrogen enters the rotary kiln through a dry gas guide screw for replacement and heat removal, an oil and gas pipeline is preheated, direct cooling tower spraying cooling water and indirect cooling tower circulating cooling water are put into use, a coal gas fan is started for system circulation, and an electrical tar precipitator outlet is opened to a rotary kiln starting line valve; the invention further discloses a rotary kiln quality improvement system, the rotary kiln pyrolysis process preheating and replacement method is adopted, the start-up time is effectively shortened, the investment and operation cost is saved, and meanwhile a foundation is laid for long-period stable operation of the system.

The utility model discloses a PLAN52 sealing system spacer fluid separating and recycling system which comprises a sealing oil siphon tank, the sealing oil siphon tank is connected with a chemical pump through a circulating unit, a circulating water mechanism is connected in the sealing oil siphon tank, the top of the sealing oil siphon tank is connected with a torch-removing system pipeline, and the torch-removing system pipeline is connected with a torch-removing system. The side wall of the sealing oil siphon tank is connected with a storage tank through a separation system, the separation system is arranged close to the top of the sealing oil siphon tank, and a backflow system is further connected between the storage tank and the sealing oil siphon tank. By fully utilizing the volatility of a medium, spacer fluid containing the medium is introduced into the storage tank and is separated in the introduction process, and the separated spacer fluid can be timely collected and supplemented into the siphon tank, so that the loss of the spacer fluid is reduced, the daily spacer fluid supplementing frequency is reduced, the service life of the mechanical seal is effectively prolonged, and the service life of the mechanical seal is prolonged. And the pump is prevented from being damaged by the loss of the spacer fluid.

A method and apparatus for operating a DC plasma torch. The power supply used is at least two times the average operating voltage used, resulting in a more stable operation of the torch. The torch can include two concentric cylinder electrodes, the electrodes can be graphite, and the plasma forming gas can be hydrogen. The power supply provided also has the capability of igniting the torch at a pulse voltage of at least 20 kilovolts.

Provided are a systems and methods for continuously providing a metal wire to a welding torch for manufacturing objects by solid freeform fabrication to provide continuous deposition of metal to the freeform object, especially objects made with titanium or titanium alloy wire.

The invention discloses a torch system, and belongs to the technical field of gas treatment.The torch system comprises a first pipeline, a first torch, a second pipeline, a second torch and a first switching pipeline, and the first torch is connected with the gas outlet end of the first pipeline; the second torch is connected with the gas outlet end of the second pipeline; the first switching pipeline is connected with the first pipeline and the second pipeline. The first pipeline is configured to enable the first pipeline to be communicated with the second torch when the first pipeline is not communicated with the first torch, and to enable the second pipeline to be communicated with the first torch when the second pipeline is not communicated with the second torch. By arranging the first switching pipeline to connect the first pipeline and the second pipeline, when the first torch or the second torch is subjected to troubleshooting, flare gas of different pipelines can be switched to a normally-working torch for combustion, torch switching and overhauling are facilitated, continuous production of the production device is guaranteed, and the production efficiency is improved. And the production efficiency and the safety can be effectively improved.

Techniques of processing a flare gas include operating a flare gas piping network to output a flare from a plurality of flows of a purge gas in purge gas headers coupled to a main header, and during operation of the flare gas network to output the flare from the plurality of flows of the purge gas: obtaining a fluid pressure of the flow of the purge gas at each purge gas header; obtaining a fluid temperature of the flow of the purge gas at each purge gas header; and obtaining a rate of the flow of the purge gas at each purge gas header; and based on the obtained fluid pressures, fluid temperatures, and rates of the flows of the purge gas, determining an optimized flow velocity of the purge gas at each of the plurality of purge gas headers.

The invention discloses an integrated anaerobic fermentation self-heating biogas production system and method, and belongs to the technical field of biomass energy. In the system disclosed by the invention, a thermal medium outlet of a solar heat collection unit is connected with a thermal medium inlet of a heat storage unit; a heat medium outlet of the heat storage unit is connected with a heat medium inlet of the anaerobic fermentation unit; a gas outlet of the anaerobic fermentation unit is respectively connected with the post-treatment system and the torch incineration device; a natural gas outlet of the post-treatment system is connected with the torch incineration device; a waste heat outlet of the post-treatment system is connected with a thermal medium inlet of the anaerobic fermentation unit; a cold medium outlet of the anaerobic fermentation unit is connected with a cold medium inlet of the heat storage unit; and a cold medium outlet of the heat storage unit is connected with a cold medium inlet of the solar heat collection unit. The system solves the technical problem that an existing method is high in energy consumption and difficult to achieve efficient operation of the whole system.

The invention designs an environment-friendly blowout device suitable for a high-salinity gas well, and belongs to the technical field of unconventional petroleum and natural gas extraction. The device comprises a two-stage concentric liquid remover and a combustion purification system which are connected in sequence. The two-stage concentric liquid remover realizes efficient separation of gas, liquid and solid phases through two-stage centrifugal separation. And a self-adaptive liquid discharge and gas control mechanism is arranged at the bottom of the two-stage concentric liquid remover, so that flow fluctuation self-adaptive sealing can be realized. Pretreated gas enters a combustion tank, is discharged through a torch pipe and is ignited, and generated combustion gas and solid particles are sprayed and purified in all directions and sprayed liquid is recycled through a spraying and recycling device above the combustion gas and the solid particles. The device integrates multiple technical functions such as buffering and pressure stabilizing, multi-phase separation, all-directional spraying purification, fire-liquid isolation, flow fluctuation self-adaption, automatic sealing, explosion prevention and fire retardance, the three-phase separation efficiency is remarkably improved, salting-out particles entering the environment are reduced, and equipment and technical supports are provided for green development of a hypersalinity gas well.

The invention provides an electric cracking furnace system and an electric cracking furnace system operation method. The electric cracking furnace system comprises an electric cracking furnace, a gas replacement module, an energy storage module and a torch module; the electric cracking furnace comprises a replacement gas cavity and an electric heating cracking cavity arranged in the replacement gas cavity; a replacement gas outlet of the replacement gas module is connected with a replacement gas inlet of a replacement gas cavity of the electric cracking furnace, and a replacement gas component detection inlet of the replacement gas module is connected with a replacement gas outlet of the replacement gas cavity of the electric cracking furnace; a feed port of the torch module is connected with an electric heating cracking cavity of the electric cracking furnace, and the torch module is used for receiving materials in the electric heating cracking cavity when the electric cracking furnace has abnormal working conditions; a high-temperature medium outlet of the energy storage module is connected with an electric heating cracking cavity of the electric cracking furnace, and the energy storage module is used for providing a high-temperature medium for the electric heating cracking cavity when the torch module receives materials in the electric heating cracking cavity. The electric cracking furnace system ensures long-period stable operation of the electric cracking furnace through the gas replacement module, the energy storage module and the torch module.

An apparatus for powder spheroidisation comprises a microwave cavity (20), a plasma chamber (35) that has an inner wall and is located in the microwave cavity, a confinement tube (3) connected to the plasma chamber, a receptacle for a mixture of a process gas and a powder precursor, the receptacle being connected to the confinement tube to feed said mixture as an incoming gas flow to the plasma chamber, in order to produce a plasma torch therein by coupling the gas flow with microwave radiation, and a flow divider (110) that is located within the confinement tube at the entrance of the plasma chamber, the flow divider providing a broad passageway (118) and a narrow passageway (113), and causing the incoming gas flow to separate into a central gas flow through the broad passageway, and a peripheral gas flow through the narrow passageway.

The invention relates to the field of waste gas purification, in particular to a waste gas anhydrous treatment device which comprises a gas inlet unit, a heat source unit, a reaction unit, a cooling unit, a slag collecting unit and a tail gas discharging unit. The gas inlet unit comprises a gas inlet pipe, and the gas inlet pipe can convey waste gas into the reaction unit; the heat source unit comprises any one of a plasma torch head, an ignition combustion flame gun and a high-temperature heating rod, and the heat source unit is mounted on the reaction unit; according to the designed water-free waste gas treatment device, waste gas is combusted through cooperation of the heat source unit and the reaction unit, products are cooled in the position of the reaction unit in a mixed mode of air cooling and water cooling when being cooled, sufficient combustion of the waste gas is guaranteed, meanwhile, the whole reaction unit can be protected, and the service life of the reaction unit is prolonged. The purposes of reducing the use amount of energy, reducing the generation of waste water and saving water are achieved.

The utility model provides a treatment device of a system for reducing vent gas to enter a torch during starting of a coal hydrogen production and synthesis ammonia device, which comprises a gasification washing tower which is respectively connected with a gasification torch-removal vent pipeline valve, a gasification crude synthesis gas delivery valve and a crude synthesis gas inlet heating furnace valve through pipelines, the gasification torch-removing emptying pipeline valve is connected with a conversion device heating pipeline emptying valve through a pipeline, and the conversion device heating pipeline emptying valve is respectively connected with a first water separator, a purification tank A inlet valve and a purification tank B inlet valve through pipelines; the bottoms of the purification tank A inlet valve and the purification tank B inlet valve are connected with purification tanks through pipelines. According to the treatment device for reducing the discharged air to enter the torch system during the start-up of the coal hydrogen production and ammonia synthesis device, the problem of low temperature of crude synthesis gas produced by a gasification device during the start-up stage is effectively solved in the existing coal hydrogen production and ammonia synthesis project production process, and waste caused by the fact that the crude synthesis gas is fed into the torch system due to low temperature is avoided.

The invention discloses a combustible gas torch burner, and belongs to the technical field of burners. A combustible gas torch burner comprises a burner body, a mixing chamber is fixedly connected to the interior of the burner body, and an air inlet pipe is fixedly connected to the bottom face of the mixing chamber. According to the combustible gas torch burner, a motor rotates forwards and backwards to drive a rotating shaft to rotate, so that a movable arc disc rotates forwards and backwards to drive a slope-shaped sliding rail to move, dynamic movement of a first sliding column and a second sliding column is adjusted, and the overturning amount of a first conical plug and a second conical plug can be adjusted; the gas output of the combustible gas inlet pipe and the combustible gas outlet pipe can be dynamically adjusted in time, sufficient mixing of air and combustible gas is controlled, the adaptive mixing ratio of the air and the combustible gas is guaranteed, sufficient combustion of mixed gas is guaranteed, generation of harmful floating pollutants is reduced, the atmospheric environment is protected, and waste of combustible gas resources is reduced.

An apparatus for treating gaseous pollutant with plasma comprises a microwave source generating a microwave oscillation; a waveguide component coupled to the microwave source; and a resonant cavity coupled to the waveguide component, the microwave oscillation is substantially propagated toward a waveguide direction, the resonant cavity comprises a first chamber and a second chamber, the waveguide direction is substantially parallel to a reference axis defined in the first chamber, the first chamber has an inner wall surrounding the reference axis, the inner wall comprises a first inner wall obliquely inclined toward the reference axis and a second inner wall substantially parallel in respect to the reference axis relatively, an area of the first inner wall is larger than that of the second inner wall so that the first chamber has a tapered space, and the microwave oscillation interacts with an ignition gas in the second chamber to generate a torch.

The invention discloses a low-temperature flare gas heat exchange device based on a U-shaped heat exchange tube and a method thereof, and belongs to the technical field of cryogenic equipment. The heat exchange device provided by the invention comprises a barrel body, a sealing head, a tube pass tube box, a tube pass tube plate, a heat exchange tube, a steam tube and a steam injection tube, wherein the heat exchange tube is a U-shaped heat exchange tube. The upper part of the cylinder is provided with a steam pipe through hole and a pressure balancing vent hole, and the bottom of the cylinder is provided with a water injection port and a drain outlet. And a heat exchange tube is arranged in an inner cavity of the cylinder body and is communicated with the tube pass tube box through a tube pass tube plate. The lower end and the upper end of the tube pass tube box are respectively connected with the air inlet pipe and the air outlet pipe; the ends, away from the tube pass tube plate, of the heat exchange tubes are provided with anti-short-circuit partition plates. A liquid level control interface is arranged on the side surface of the barrel. The heat exchange device provided by the invention is compact in design, space is saved, the use of materials is reduced, the manufacturing process is simplified, the heat transfer efficiency is improved, the performance is improved, the heat exchange device has remarkable economical efficiency and high performance advantages, and the manufacturing cost is reduced.

The invention relates to the technical field of welding tools, in particular to a welding tool for torch barrel machining, which comprises a track and a support frame, the support frame is used for horizontally placing a torch barrel, a mounting frame is arranged on the track, a mounting rod is slidably connected to the mounting frame along the vertical direction, and three support rods are uniformly arranged on the mounting rod at intervals in the circumferential direction; the supporting rods are parallel to the mounting rod, and a first driving assembly for driving the three supporting rods to move in the radial direction of the mounting rod is arranged on the mounting rod; two swing rods are rotationally connected to the supporting rod, a second driving assembly for driving the two swing rods to rotate away from each other or close to each other at the same time is arranged on the supporting rod, the two swing rods are connected with pushing pieces respectively, the pushing pieces are in sliding connection with the swing rods in the direction perpendicular to the swing rods, and third driving assemblies for driving the pushing pieces to move are arranged on the swing rods. According to the welding tool for torch cylinder machining, the accuracy of the welding position between the mounting frame and the air inlet is improved, labor consumption is reduced, and the production cost is reduced.

The invention relates to a pure oxygen pulverized coal burner which comprises a pulverized coal bin, a pulverized coal conveying cylinder, an oxygen header pipe, oxygen spray pipes and burner blocks. The oxygen spray pipe and the pulverized coal conveying cylinder extend into the burner block; a pulse valve is arranged on the oxygen spraying pipe, an accumulation groove and a pulverized coal striking head are arranged at the tail end of the pulverized coal conveying barrel, pulverized coal falls into the accumulation groove through conveying of the pulverized coal conveying barrel, and the pulverized coal striking head is connected with a striking head driving motor through a striking head transmission shaft to rotate at a high speed to strike the pulverized coal falling into the accumulation groove. Compared with the prior art, the pulse jet oxygen is supplied after the pulverized coal is scattered and scattered, so that the torch time is effectively shortened, and the thermal radiation of a continuous combustion torch to a nozzle is eliminated to a great extent. The supply of the pulverized coal and the supply of the oxygen can be flexibly controlled through the opening and closing interval time of the valve, and the power of the combustor can be conveniently adjusted according to the required furnace temperature and heat supply amount, so that the oxygen and the pulverized coal can be fully and uniformly mixed regardless of the power, and the optimal air-fuel ratio is achieved.

The novel environment-friendly torch comprises a torch body, a combustion part and a supporting part are arranged on the torch body, the combustion part is located above the supporting part, an air outlet is formed in the bottom of the combustion part, an air inlet, an air extracting pump and an air collecting chamber are arranged on the supporting part, and the air inlet, the air outlet and the air collecting chamber are communicated with an air collecting opening. The gas collecting chamber is electrically connected with the gas collecting opening and the sucking pump, natural hydrate fuel is placed at the bottom of the gas collecting chamber, the space between the bottom of the gas collecting chamber and the supporting part is filled with the thermal insulation layer, the fuel is decomposed into methane in the gas collecting chamber, and the combustion effect can be improved by mixing the methane and air through the sucking pump. Compared with fuel such as propane, the natural gas hydrate is small in size and long in combustion time, compared with hydrogen fuel, the natural gas hydrate only needs a low-pressure condition and is better in safety, more importantly, the fuel is rich in reserves, only a small amount of carbon dioxide and water are generated after combustion, and the natural gas hydrate fuel is environmentally friendly, low in manufacturing and obtaining cost, simple in storage mode and suitable for popularization and application. And the economic benefits of producers are greatly improved.

The present invention discloses a device and method for recovering the coldness of residual liquid in a synthesis gas CO cryogenic separation system, and belongs to the field of chemical process. When the synthesis gas CO cryogenic separation system is shut down and drained, the temperature can reach -190°C due to the large amount of low-temperature residual liquid stored in the cold box. The conventional treatment method is to send the low-temperature residual liquid to the flare gas heater through ambient gasification, and discharge it as room-temperature flare gas after heat exchange with saturated steam. When the amount of low-temperature residual liquid is large, this method takes a long time to vaporize the low-temperature residual liquid; or nitrogen is used to cool and gasify the low-temperature residual liquid to produce low-temperature flare gas, which is then sent to the flare gas heater for heat exchange. This method increases nitrogen loss, increases the load of the flare gas heater, makes its equipment size larger, and increases cost. The present invention utilizes the high-grade low-temperature coldness of the low-temperature residual liquid in the CO cryogenic separation system to convert room-temperature nitrogen into liquid nitrogen for storage and recovery, thereby reducing nitrogen loss, reducing 0.5MPaG steam loss, and reducing flare gas emissions.

The utility model discloses a flare gas recovery power generation device which comprises a flare gas liquid separation tank, a Stirling generator set, a flare head and a controller, a flare gas outlet of the flare gas liquid separation tank is connected with the input end of a flare gas main pipeline, and the flare gas main pipeline is connected with a plurality of branch pipelines. The tail ends of the branch pipelines are connected with the torch head and one or more Stirling generator sets respectively, the Stirling generator sets are connected in parallel, first pressure regulating valves are arranged on the branch pipelines connected with the Stirling generator sets respectively, and safety regulating parts are arranged on the branch pipelines connected with the torch head. A pressure transmitter is arranged on the flare gas main pipeline, and the first pressure adjusting valve, the safety adjusting part and the pressure transmitter are in communication connection with the controller. The device is reliable in safety performance, small in occupied area, low in weight, low in cost and flexible in power utilization mode.

1. The name of the design product: biogas torch (premixed type). 2. The use of the design product: for processing biogas generated in the production process of sewage treatment plants, waste treatment plants, farms, chemical plants, etc.; biogas generated by anaerobic fermentation in the sewage treatment of pharmaceutical factories, distilleries, paper mills, kitchen waste treatment, landfill leachate, food factories, beverage factories, etc. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view 1. 5. The top surface of the design product is not easily visible or invisible during use, and the bottom view is omitted. The bottom surface of the design product is not easily visible or invisible during use, and the top view is omitted.

1. The name of the design product: floor fan (torch style). 2. The use of the design product: for blowing and cooling, etc. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view 1.

The present application provides an apparatus and method for recovering nitrogen discharged from waste water by washing with liquid nitrogen, comprising: a U-tube circulating water heater, a first pipeline, and a second pipeline. The inlet end of the U-tube circulating water heater is connected to the middle section of the second pipeline through the first pipeline, and the outlet end is used to connect to the fuel gas pipeline network; one end of the second pipeline is connected to the hydrogen separator; a control valve and a shut-off valve are provided on the second pipeline, and the control valve is located between the first pipeline and the hydrogen separator, and the shut-off valve is located between the first pipeline and the end of the second pipeline away from the hydrogen separator. The present invention effectively recovers CO in the discharged nitrogen. Each set of equipment can recover more than 170 NM3 / h of fuel gas and 100 NM3 / h of effective gas, with an annual benefit of more than 640,000 yuan, and a significant energy-saving effect. At the same time, due to the reduction of cold torch discharge, steam consumption is indirectly saved, and the phenomenon of long-term ice accumulation in the buffer tank is completely eliminated, which greatly improves the sanitation around the buffer tank and on the ground.