DARPA Program Develops World’s Smallest Vacum Pumps | Gizmag

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Three DARPA-funded research teams have completed a foundational study of chip-scale vacuum pumps by inventing three very different approaches to removing air from a sample chamber with a volume of one cubic millimeter, which is about one-tenth the volume of a grain of rice. These new technologies will enable many micro-scale devices which require a vacuum or a controlled flow of gas, such as Lab-on-a-Chip sensors, radio frequency MEMS switches and microscopic vacuum tubes.

Why is DARPA interested in tiny devices that operate in a vacuum? Over the past quarter of a century, a host of MEMS (Microelectromechanical Systems) and other devices have been developed. Many of these devices require microscale pumps for their operation, such as the various Lab-on-a-Chip analytical sensors, which must pump air or liquid samples through a series of testing stations on the chip. This requires real-time in-situ pumping capacity, as do the maintenance procedures performed between measurements.

There are also microscale components that require a vacuum environment for proper operation, such as radio frequency MEMS switches, microscopic vacuum tubes, and other parts that depend on electron or ion optics. Simply sealing the devices while in a vacuum chamber often does not give sufficient service life, as leaks and degassing are far more detrimental to vacuum devices on the microscale. Accordingly, such components may need a vacuum pump on the chip to maintain functionality.

There are also microscale devices which may work better in a vacuum, but don’t require that environment for simple operation. For example, a MEMS resonator, essentially a tiny tuning fork, will work fine at atmospheric pressure. However, some of the air sticks to the surface of the tuning fork, changing the effective mass of the resonator. In addition, the wind stirred up by the vibration of the resonator damps the vibrations. Together, these effects change the resonant frequency of the resonator and cause the resonance to be less sharp. Perhaps worse, these alterations will vary with the temperature in which the overall system is functioning even if the MEMS resonator is hermetically sealed in a gas.

These and other potential advantages of integrating effective and efficient vacuum pumping capabilities into microscale systems triggered DARPA’s interest in finding some practical approaches through which these desirable properties can be attained. In 2008, it issued a request for proposals for its Chip-Scale Vacuum Micro Pumps (CSVMP) program asking for the development of microscale vacuum systems satisfying (or at least addressing) the following points.

DARPA sought a vacuum system no bigger than a US penny that is able to produce a vacuum of less than 100 microPascals (uPa, a billionth of atmospheric pressure) in a vacuum chamber with at least a cubic millimeter of volume (about the size of a grain of coarse sand). The vacuum system was to use less than a quarter of a watt, and contain instruments to accurately measure the pressure in the chamber.

To help appreciate the magnitude of the task DARPA had posed, consider the Creare Engineering miniature turbo/drag pump, considered to be the world’s smallest practical turbo pump produced by conventional machining tools. The pump is some 3.8 cm in diameter with a length of 8 cm, making it slightly larger than a D-cell battery. It weighs about 150 g (5.3 oz), and can reach an ultimate pressure of a few uPa. The pumping speed is four liters/second at a rotor speed of 200,000 rpm, and consumes about 2 W in doing so. This pump needs to be followed by a roughing pump as it cannot pump against atmospheric pressure.

So while the Creare pump can meet DARPA’s vacuum pumping requirements (it is more than capable of pumping a mm-scale chamber down to 100 uPa), it is nearly 200 times too large in volume, and uses ten times too much power in doing so. And because it is a specially designed pump made in very small numbers for NASA applications including on the Curiosity rover, the price is likely out of proportion when used to make a US$10 MEMS chip work properly.

Based on their responses to DARPA’s request, three research teams from the University of Michigan (U-M), MIT, and Honeywell Corporation, were chosen to mount independent R&D efforts to meet DARPA’s requirements. They responded to this challenge by inventing a series of novel microfabricated chip-scale vacuum pumps. Let’s take a look at a few of these.

University of Michigan

The single pumping cell (two-stage) of the Scalable Michigan gas micropump (left), and pho...

U-M researchers developed three different pumps. The first is a high-frequency 24-stage resonant peristaltic roughing pump (PDF). They used a scalable, resonant design that produced a very large flow rate of 0.36 cc/minute and allowed it to reduce the pressure of a sample chamber to about 97 kPa from the atmospheric pressure of 101.3 kPa. The theoretical limit on the performance of such a pump is to reduce the pressure to around 1.5 kPa, The lower performance of the 24-stage pump is thought to result from leakage of the microvalves in the pump and non-ideal motions of the membrane that moves air around within the pump.

Simplified operation of a Knudsen pump that produces vacuum through thermal transpiration ...

The U-M team also developed a 48-stage Knudsen vacuum pump (PDF). The Knudsen pump is unusual in that it has no moving parts. Instead, it works on the principle of thermal transpiration. If you connect two gas-containing chambers through a channel, the gas molecules will move between the two chambers until the pressure in the system is constant. If one of the chambers is now heated while the other remains at its original temperature, the pressure in the hot chamber will increase.

Since the overall system still wants to be in mechanical equilibrium, some of the gas molecules move from the hot chamber into the cold chamber. If you then close a valve between the hot and cold chambers, and let the temperature of the hot chamber return to the original value, the pressure in the hot chamber will be less than before the heating-cooling cycle was performed. The pair of chambers and appropriate valves acts as a vacuum pump.

The U-M 48-stage Knudsen pump can reduce the pressure in a sample chamber from atmospheric pressure to less than 7 kPa, or to less than 1 kPa if followed by a backing pump. These compression ratios are about ten times larger than had been previously obtained. At 1.35 W, the power requirement is a bit larger than the DARPA requirement, but optimization of the thermal properties of the pump structure should significantly reduce the power required.

U-M’s high-vacuum pump was a microplasma sputter-ion pump, which embeds gas molecules in a material layer constantly being deposited during the operation of the pump. They were able to obtain vacuums down to 1 Pa, and showed evidence that the type of pump is capable of ultimate pressures smaller than 1 uPa.

MIT

The MIT engineering team also developed three-pumps, including a displacement roughing pump, a field ionization pump, and an electron impact ionization pump. The latter two pumps operate by using carbon nanotubes to provide large electric fields to ionize gas molecules in the pump, and then using electric fields to embed the ions into a surface, thereby removing them from the vacuum system.

A two-stage roughing pump with curved surfaces developed by a team of MIT researchers (MIT...

MIT’s displacement pump (PDF) uses curved pumping surfaces to obtain record compression ratios up to 4.6 per pumping stage. Given a system goal that the roughing pump provide a pressure of 4 kPa to support the high-vacuum pumps, this means that two stages of rough pumping should suffice, rather than the 24-stage pumps developed by the Michigan team.

Six operational steps of the MIT microfabricated displacement pump (Image: B. Dodson)

The visual above explains the operation of the MIT mechanical pump. It is essentially a piston-type pump, with active inlet and outlet valves. This pump was actuated and powered by pneumatic actuators, but in actual application would probably include electrostatic actuators for this purpose.

Honeywell

Honeywell may well have developed the most ambitious pump of the DARPA project, a micromachined version of a turbomolecular pump, which is like a turbine in reverse. Operating at pressures below about 1 kPa, this approach was probably chosen because of Honeywell’s past work on developing micro-scale gas turbine engines to provide electrical power.

A micro-scale turbomolecular pump developed by Honeywell can achieve high vacuum condition...

The heart of the Honeywell pump is an exquisitely detailed turbine rotor about 1.5 cm (0.6 in) in diameter. Very little quantitative information has emerged on this pump, but judging from the figure, the outer 2.5 mm (0.1 in) of the rotor is covered with tiny turbine blades, so angled that, as the rotor spins, the blades pick up air from the central region of the rotor, and throw it out the edge of the rotor. There appear to be about 2,000 rotor blades, each of which is about 60 microns wide, 60 microns tall, and 10 microns thick.

Although the Honeywell pump requires a roughing pump to reach operating levels of pressure, it has strengths and weaknesses that differ from those of other micro-scale vacuum pumps. It will probably find a solid position in the quiver of chip-scale vacuum systems.

“There have never been ionic or mechanical gas pumps at the microscale before,” says DARPA program manager Andrei Shkel. “The CSVMP program has demonstrated both and more. The smallest commercially available pumps are the size of a deck of cards, which dwarf the vacuum electronics and sensors we want to attach our pumps to. These pumps are not only 300 times smaller than off-the-shelf pumps and 20 times smaller than custom-built pumps, but they also consume approximately 10 times less power to evacuate from atmospheric pressure to milliTorr pressures.”

Although the CSVMP program was initially focused on developing microscale pumps for for better chemical and biological pathogen detection through small mass spectrometry gas analyzer applications, other potential applications for the technology became apparent.

“These microscale gas pumps may ultimately be required for laser-cooled atomic clocks, accelerometers and gyroscopes,” says Shkel. “Laser cooling systems require vacuums, but are often significantly smaller than the pumps themselves. It is possible that these pumps will help enable smaller, more accurate atomic clocks.”

SOURCE:  http://www.gizmag.com/darpa-mems-smallest-vacuum-pumps/27883/

Electromagnetic Pipeline Transport System | Capsu.org

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Abstract

This paper presents a description and cost model results for a new bulk material pipeline transport system. A demonstration which uses a linear synchronous motor to move vehicles is under construction at the IMC-Agrico Company in Lakeland, FL. The demonstration utilizes 276 m (700 feet) of 610 mm (24 inch) diameter cylindrical cast “waste water” fiberglass tube, and contains a 79 m (200 foot ) long accelerator/decelerator section, a switch, and load and unload stations. The test vehicle traverses back and forth, obtaining a peak speed of 17.9 m/s (40 MPH.) The 2.39 m (6 foot) wheelbase vehicle uses six-wheel assemblies at each end of a rotating hopper, and has a payload capacity of 273 kg (600 pounds.) The vehicle carries an array of neodymium-iron boron permanent magnets which interact with the linear motor mounted on the outside of the tube to provide propulsion, and with external coils to provide an electromagnetic switch function. A preliminary economic model has been built to estimate total system cost and to investigate the trade-off between variables such as annual capacity goals, pipe diameter, vehicle speed, headway and number of coupled cars.

Introduction

Pneumatic capsule pipelines have a long history, and there are several large scale systems in current use. Conventional pneumatic systems use external blowers to move the column of air together with the capsules in the pipe. Full-diameter valves are used to control the injection, removal and subsquent return of capsules. Various practical limits tend to constrain the throughput of these systems and limit their cost effectiveness. We believe that by making use of electromagnetics we can improve on the constraints which limit throughput.

Our interest in capsule pipelines has been driven by the desire of the Florida Phosphate Industry to find a cost effective way to reduce the environmental impact of conventional transportation of their very large quantities of material. They project, for example, as many as 27 million tonnes (30 million tons) per year of finished product flowing out from the Port of Tampa. Trucks carry the bulk of current production, and place a burden on the already stretched feeder and highway infrastructure in the region. A 48 km (30 mile) pipeline from the mining region to the port would be a potential solution, but would need to be sufficiently cost effective relative to more conventional transportation to result in a satisfactory return on capital. Preliminary economic studies have been sufficiently promising to result in a willingness by the phosphate industry to undertake exploratory R&D.

Since beginning our explorations, we have also received expressions of interest from a large mining company interested in transport of ore from deep mines to their surface mills, and from a large cement company interested in a viable alternative for their more difficult long-length conveyor belt applications.

FIGURE 1: Cross-section through pipe and capsule mid-section.
Diagram: Cross-section through pipe and capsule mid-section.
FIGURE 2: Capsule with 4-pole magnet structure.
Diagram: Capsule with 4-pole magnet structure.
FIGURE 3: Single phase of the three phase Linear Synchronous winding module (not shown full length)
Diagram: Single phase of the three phase Linear Synchronous winding module.

Prototype System Description

A cross section through the pipe containing a typical vehicle is shown in Figure 1, and the vehicle is shown separately in Figure 2. The linear synchronous motor “stator” winding is mounted on the outside of the tube leaving the inside of the tube free of obstructions. The permanent magnet assembly mounted on the vehicle consists of four poles, alternately north and south. A linear synchronous motor concept was chosen over a linear induction motor concept because of it retains reasonable efficiency at large operating gaps. The gap between the magnet face and the effective centerline of the winding is 32 mm (1.25 inches.)

Pipe:

Because the winding is on the exterior of the tube, the tube must be made from a non-conducting material. A cast fiberglass “waste water” pipe product is used for the straight sections, and is supplied in 7.9 m (20 foot) lengths with a 15 mm ( 0.6 inch) wall. The curved sections are also fiberglass, but are built on an interior removable mandrel. The sections are joined by standard sealed couplings. The pipe can be run at ground level, in elevated sections, or underground.

Vehicle:

The vehicle consists of a cylindrical open-top hopper 508 mm (20 in) in diameter by 1219 mm (48 in) long, attached to wheel carriers at each end through pivot bearings. This allows the hopper and the wheel assemblies to rotate independently around the pipe line central axis. The wheel carriers each have six wheels spaced at equal 60 degree angles. The wheels are 150 mm (6 in) diameter polyurethane coated standard industrial units with sealed ball-bearings. The overall length of the vehicle is 2.36 m (6 feet.) The magnet assembly occupies a 90 degree by 1219 mm (4 foot) long sector at the bottom of the vehicle, and is hung from the central shaft at each end of the hopper section through bearing mounts, to allow rotation independent of both the hopper and the wheel assemblies. This feature is used in switching and unloading.

The fully loaded capsule weighs 545 kg (1200 pounds), of which 273 kg (600 pounds) is payload. The ratio of payload to overall weight is lower than one might have postulated from conventional capsule systems. This is largely a consquence of the need to carry an on-board magnet system, which weighs 91 kg (200 pounds.) Additional tare weight reductions may be possible as the project moves beyond the prototype stage.

Magnet Assembly:

The magnet assembly consists of an array of individual blocks 5 cm x 5 cm x 1.9 cm deep (2″ x 2″ x 3/4″), magnetized parallel to the 1.9 cm dimension. They are located on a curved back-iron plate 610 mm by 1220 mm long by 12.7 mm thick (2 feet by 4 feet by 0.5 inches thick) which is hung from the central shaft at each end of the hopper section. The 80 individual magnet blocks are arranged in sets of 28 to form four poles, two north and two south. The poles have a “pole pitch” of 305 mm (12 inches), and a repeat pitch of 610 mm (24 inches.) The magnets blocks are magnetized prior to mounting on the back iron.

Linear Synchronous Motor Winding:

The linear motor windings are wound in 7.09 m (18-foot-long) modules and attached to the outside of individual 7.9 m (20-foot-long) pipe sections. Each module is wound from three continuous lengths of #6 copper cable, insulated for 600 volt outdoor service. Each length forms one phase of the three-phase winding, and is wound back and forth 14 times using special tooling. A single phase of the winding (artifically foreshortened) is illustrated in Figure 3. A laminated iron 12.5 mm thick backing is included ouside the winding to double the effective permanent magnet field at the winding, reducing the power requirement by a factor of four.

Power Conversion and Control:

A standard 100 HP commercial four-quadrant motor drive is used to drive the synchronous motor modules. The drives are outfitted with proprietary control systems to enable them to automatically synchronize the LSM, and to interface with the global control system. An output frequency of 30 hz is synchronous with 17.9 m/s (40MPH.) Ten modules in series are required to accelerate a fully loaded vehicle to 17.9 m/s. In cruise sections of the pipe, periodically spaced motor modules are used to re-accelerate the capsules which have been slowed by wheel bearing and air friction. The impact of periodic windings on system operation and economics is discussed in later sections.

In most rotary and linear synchronous motor applications a feed-back loop is required between the position of the “rotor” and the phase of the stator magnetic traveling wave.

In the pipeline capsule “freight” application, however, where the load is insensitive to the jerk which accompanies position hunting, the motor can be operated open-loop without difficulty as long as the phase angle is not advanced beyond a limit. This eliminates the need to continuously sense position of the vehicle. Instead, position and velocity are checked only at the entrance to each motor section as the car passes over a simple magnetic sensor.

A global control system is required to keep the capsules properly spaced. Each time a vehicle passes over a boost winding, the global controller adjusts the speed appropriately. A phase difference is maintained between the capsules assuring that all do not simultaneous pass over boost windings, thus smoothing out the power peaks. Information fed-back from the local drives can also modify the global system; for example, capsules that do not respond in an anticipated manner, and may require maintenance can be flagged.

Load and Unload Stations:

A load station consists of an accumulation hopper feeding a metering device, which in turn dumps on command through a chute into the at-rest hopper section.

The unload station needs to rotate the hopper 180 degrees, and have a clear path for the load to gravity dump. This requires that the magnet assembly be rotated out of the way, and that there be no vehicle support directly below the hopper. A preferred approach is to rotate the magnet assembly 180 degrees before entering the unload station using the same technique used in the switch, and to then use passive iron elements on the top of the tube to provide sufficient upward attractive force to carry the full weight of the loaded vehicle. The lower 180 degrees of the pipe can then be removed without loss of support. The magnet rotation is also used to rotate the load hopper.

Experimental dumps of phosphate rock with varying levels of moisture indicate that a minimum of 1.5 seconds is required to dump the load. To provide a time allowance for positioning the capsule and releasing it, we have set 2 seconds as the minimum time interval allowed for each capsule to spend within the unload station.

Capsules can be operated singly or in coupled sets. Coupling two capsules, for example, increases the launch interval by two, reducing the number of required parallel load and unload stations, but increases the complexity of those stations.

Switch:

Throughput of a given dimension pipeline can be increased as the time interval between capsules (or an articulated set of capsules) is decreased. If the time interval between capsules becomes shorter than the minimum time required in an unload station, parallel unload stations must be added with switches to accomodate the increased throughput.

An external winding interacts with the magnet assembly on the capsule to provide the switch function. A “street Y” switch section in the pipeline is provided. Prior to entering the switch, the rotatable magnet assembly on the vehicle is swung to the horizontal position by an external winding on the pipe, and then held in that orientation by passive iron elements in the wall of the tube. The elements carry through the curved section of switch until the vehicle has safely re-entered the pipeline, at which point the magnet assembly rotates back to the bottom. In the default mode, the capsule travels directly through the straight branch, with any necessary lateral support provided by passive iron elements in that wall.

Demonstration Project:

A demonstration project is under construction to test the feasibility of the system concept and the various components. Two hundred seventy six meters (700 feet) of 610 mm (24 inch) diameter pipeline are being constructed. A vehicle is loaded and accelerated to 17.9 m/s (40 MPH), coasts to a stop in climbing a 24 m (60 foot) elevation hill; re-accelerates to 17.9 m/s (40 MPH) in decending the hill, is decelerated to zero, unloaded, and recycled through the process. The switch is located between the accelerator and the hill.

Preliminary systems integration tests were completed in March, 1999. Two motor modules were used to cycle a vehicle between the ends of an 80 foot pipeline section at a vehicle speed of 2.7 m/s (6 MPH.) A separate wheel test ran fully loaded wheels at 17.9 m/s (40 MPH) for 300 hours without noticeable wear.

The field installation began in July, 1999, and site integration tests will begin in September. The present phase of testing is scheduled to be complete in February, 2000. Photographs of several components are shown in Figure 4.

FIGURE 4.
Image: Demonstration Project.

Motor Coverage

In a freight transport pipeline there is no need for the capsules to maintain a constant velocity, and therefore no need to cover the entire length of the line with motor windings. Rather the capsules can coast between periodically spaced motor modules which boost the speed lost to wheel friction and moving air in the pipe. As noted in the economic studies, the fraction of the pipeline occupied by motor windings has a significant impact on the overall system capital cost.

The fraction of motor coverage required is a function of the allowed loss of speed between motors, the capability of the motors, the pipeline and capsule characteristics and the velocity and spacing between capsules. For the prototype 610 mm (24 inch) pipeline and 545 kg (1200 pound) loaded capsule, the minimum percent coverage required on flat ground is 5% if vehicles are traveling at 1 second intervals and are permitted to lose 10% of their 17.9 m/s (40 MPH) speed before re-acceleration. Since two 7.9 m (20-foot ) motor modules are sufficient to re-establish the velocity of a passing capsule, 5% coverage represents a pair of modules every 281 m (712 feet.)

The individual capsule speed loss resulting from moving air in the pipeline, depends on how much air is being moved by each capsule, which inturn depends on the time interval between capsules. If the interval in the above example is lengthened from 1 to 3 seconds, each capsule must move 3 times as much air, and will have higher losses. A motor coverage of 8% is required in this case, requiring two motor modules every 175 m (443 feet.) At 3 second intervals, the losses due to moving air are comparable to the wheel friction losses, assuming a coefficient of friction of 0.01 for the wheels.

While limiting motor coverage to small percentages of the total pipeline has a beneficial economic effect, it presents a potential problem of system restart after a loss of power. In the above examples (assuming level ground) the 1 second spaced capsules would coast to a stop in 158 seconds, traveling a distance of 1700 m (4320 feet); at 3 second intervals (with larger losses per capsule) they would coast for 130 seconds, traveling a distance of 1270 m (3224 feet.) With these very small percent coverage of windings, the chance that any significant number of capsules would coast to a stop over a motor segment is very low, and therefore some other strategy for restart is required. The relatively long coast times, however, do allow normal recovery from the most common power failures which are only a few seconds in duration. The capsules would simply coast to a somewhat lower velocity before being automatically re-accelerated when the power was restored.

The restart strategy chosen would depend on an assessment of the expected frequency of long duration power outages. If it were once a year, a slow recovery could be tolerated; for example, motorized “recovery” capsules could clear the pipeline. If the expectation were for much more frequent outages, a more pro-active system would be required. By way of example, a bypass pipe containing an accelerator could be provided every 1300 m (3300 feet.) In the event of a long duration power failure, coasting capsules would be switched into the bypass and held until they could be re-accelerated and re-enter the main pipeline. Addition of a 79 m (200 feet) long accelerator every 1700 m (4400 feet), would add a 5% motor coverage penalty to the capital cost. The coupling of vehicles through the air column in the pipe would be used to advantage during the re-start.

The above discussion is based on a hypothetical level-ground installation. In cases where significant altitude changes must be accomodated, motor coverage would need to be further increased.

Linear Synchronous Motor Performance

The calculated perfomance of a pair of boost modules sufficient to restore a 10 % drop in velocity is given below, and is based on the prototype design. A commercial 100 HP conventional synchronous motor drive unit is sufficent to power a module. The performance of the two motors can be seen to be somewhat different, reflecting the speed dependent characteristics. The efficiency increases with speed, but the increased back EMF developed by the vehicle motion cuts into the maximum voltage limit on the drive, decreasing the current and thrust available.

Table 1.0: 1st Boost Motor and Drive at 60 Degree Phase Angle
Variable Value Variable Value
Velocity in (m/s) 15.9 Efficiency (%) 55
Velocity out (m/s) 17 Power factor(%) 44
Time (s) 0.26 Traction power (kW) 37
Acceleration (m/s^2) 4.5 Input power (kW) 69
Thrust (N) 2242 Input power (HP) 93
Table 2.0: 2nd Boost Motor and Drive at 60 Degree Phase Angle
Variable Value Variable Value
Velocity in (m/s) 17 Efficiency (%) 58
Velocity out (m/s) 18 Power factor(%) 44
Time (s) 0.24 Traction power (kW) 37
Acceleration (m/s^2) 4.2 Input power (kW) 65
Thrust (N) 2090 Input power (HP) 88

When capsules are first introduced into the pipeline they need to be accelerated to their cruise velocity of 17.9 m/s. This requires ten modules in series. At lower speeds, for example, the initial stages of the accelerator section, the speed dependent trends illustrated by the two boost windings are more apparent. At the low speed end, the maximum thrust is limited by the available drive current and by heating in the windings. The thrust that can be provided by the modules at a given speed is related to the cosine of the phase angle between the winding drive and the magnet poles on the capsule; it is maximum when the angle is 90 degrees. If feedback control between the vehicle position and the drive phase is employed, angles approaching 90 degrees can be utilized. If the angle is reduced to 60 degrees, the system will operate stably without feedback control. The thrust at 60 degrees drops to 87 % of the maximum available, but is a reasonable tradeoff against the complexity of a feedback loop requiring continous and accurate position sensing, and the need for on-board transducers.

Economic Studies

Economic studies have been made using a preliminary costing model. The model takes engineering and unit cost inputs and projects capital and operating costs for any prospective system. Major capital cost components include pipeline, vehicles, magnet assemblies, windings and load/unload stations. The elements of operating cost include power, material costs for maintenance (taken as a fixed percentage of capital cost) and labor costs for operating and maintaining the system.

The case studies show that pipeline diameters ranging from 457 to 559 mm (18 to 24 inches) and vehicle speeds of 9 to 18 m/s (20 to 40 MPH) are generally optimum for systems operating in the 4.8 to 48 km (3 to 30 mile), l to 10 Million tons/year (Mt/y) range. Slower speeds are more optimum at short distances where the load/unload station costs are a substantial fraction of the total cost. In nearly all cases, pipeline costs are the largest single component of capital cost, whereas the second-most expensive component depends on the distance and tonnage. The model minimizes total system cost, which is defined here as the sum of the annualized capital cost plus the operating cost. Calculation of the annualized capital cost requires a choice of a minimum attractive rate of return and a time over which the return will be realized. In our studies we have fixed these at 20% and 20 years as illustrative.

Figure 5 presents the total system cost projected by the model for a 30 mile, 10 Mt/y system as a function of the pipeline diameter, at vehicle velocities of 20, 30, 40 and 60 mph. The figure shows that a minimum cost occurs in the vicinity of pipeline diameters of 18 to 26 inches, depending on velocity. Since pipeline costs are a strong function of the pipeline diameter, smaller diameters are desirable; to keep the throughput constant the smaller pipelines require higher speeds. All the constant velocity curves show a minimum point. Pipeline diameters below the minimum require such frequent launches of vehicles that the increasing number and cost of the required parallel load and unload stations and number of vehicles begins to increase the total cost. The system that minimizes total cost operates at 17.9 m/s (40 MPH), with a 559 mm (22-inch) pipeline. At higher speed, for example the 60 MPH curve shown, the increasing power penalty for moving air starts to add significant cost.

FIGURE 5: Projected total system cost as a function of pipe diameter and capsule velocity for a 30 mile, 10 Mt/year installation.
Graph: Projected total system cost.

The 59 mm (22 inch,) 17.9 m/s (40 MPH) minimum cost case would require a total of 8652 vehicles (half outbound and half returning) and seven parallel load/unload-station branches at each end of the line to handle the 10 Mt/y throughput. The capsules are assumed to be coupled in sets of three. The cost elements at this minimum cost point are summarized in the table below.

Table 3.0: Capital and Operating Cost for 17.9 m/s, 559 mm pipe Case
Capital Cost $M %
Pipeline 18.8 30.7
Vehicles 15.6 25.5
Magnet assemblies 7.8 12.7
Motor windings 7.7 12.6
Load/unload stations 5.5 9.0
Power units outbound 3.3 5.4
Power units returning 1.6 2.6
Central control 0.5 0.8
Block control units 0.4 0.7
Total 61.2 100.0
Capital recovery ($/t-mile) 0.042
Operating Cost $M/y %
Power 3.3 49.3
Maintenance 1.8 27.7
Labor 1.5 23.0
Total 6.7 100.0
Operating cost $/ton-mile 0.022
Total System Cost ($/t-mile) 0.064

Shorter haul distance case studies show higher total system costs per ton-mile, for example, rising to 0.10$/t-mile for a 10 Mt/y capacity at an 8 km (5 mile distance.) Shorter haul distances are increasingly dominated by the cost of the load and unload facilities, and minumum costs are achieved by minimizing those facilities, generally by increasing pipeline diameters and reducing speed. Lower capacity systems also have higher costs per ton-mile; for example, costs for a 5 Mt/y system at a distance of 48 km (30 miles) are 0.10$/t-mile.

The economic model uses illustrative unit costs and scaling relationships to establish the sensitivity to variables and to determine what elements are likely to dominate the costs. The estimates for some of the elements, for example the pipeline itself and the power units, can be reasonably estimated from existing data bases. Other elements such as the cost of vehicles, magnet assemblies and motor windings are much more speculative. For these elements, experience in fabrication of the prototype reduced by a factor for volume productions has been used. The reduction factor is only speculative as production engineering studies have not been done.

All examples above assumed a six percent winding coverage of the pipeline. For the 10 Mt/y, 30 mile case, if the coverage were to be increased to 12 percent, the capital cost would increase by 22 percent, increasing the total system cost by 14 percent, from $0.064/ton-mile to $0.073/ton-mile.

Conclusions

Preliminary economic studies have provided sufficient incentive for sponsorship of the demonstration project of a suitable scale to establish the feasibility of the technical approach. A follow-on project will likely be necessary before a viable product can be commercially available. Such a suitable follow-on project might be to replace truck traffic beween near-by processing plants and would serve to fully develop the technology, and establish the economics.

Acknowledgement

The project acknowledges the generous support of the Florida Institute of Phosphate Research, and the IMC-Agrico Company. We also acknowledge the financial support and technical contributions from Argila Enterprises and MTechnology, Inc.

References

Bulk Ore Transport by Linear Synchronous Motor Economic Model, Bradford A. Smith, MIT Plasma Fusion Center, 185 Albany Street, Cambridge, MA 02139; December 7, 1998.

SOURCE:  http://www.capsu.org/library/documents/0015.html

Chemistry Framework using Common Component Architecture | Ames Laboratory

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The development of emerging technologies such as molecular computing, nanotechnology, and next generation catalysts will continue to place increasing demands on chemical simulation software, requiring more capabilities and more sophisticated simulation environments.  Such software will be too complex for a single group, or even a single discipline to develop independently.  Coupling multiple physical models in one domain and coupling simulations across multiple time and length-scales will become the norm rather than the exception. These simulations will also run on more complicated and diverse hardware platforms, potentially with hundreds of thousands of processors and performance exceeding one petaFLOP/s.  This evolution will transform the way chemists must think about scientific problems, models and algorithms, software lifecycle and the use of computational resources.  Advances in chemical science critical to DOE and national challenges require adoption of new approaches for large-scale collaborative development and a flexible, community-based architecture. We propose to employ the infrastructure of the Common Component Architecture to develop interfaces among three of the most important computational chemistry codes in the world: General Atomic and Molecular Electronic Structure System (GAMESS), the Massively Parallel Quantum Chemistry program (MPQC) and Northwest Chem (NWChem).

SOURCE:  https://www.ameslab.gov/amcs/fwp/chemistry-framework

The Six Types of Chemical Reaction | Brinkster

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All chemical reactions can be placed into one of six categories.  Here they are, in no particular order:

1) Combustion: A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

C10H8 + 12 O2 —> 10 CO2 + 4 H2O


2) Synthesis: A synthesis reaction is when two or more simple compounds combine to form a more complicated one. These reactions come in the general form of:

A + B —> AB

One example of a synthesis reaction is the combination of iron and sulfur to form iron (II) sulfide:

8 Fe + S8 —> 8 FeS


3) Decomposition: A decomposition reaction is the opposite of a synthesis reaction – a complex molecule breaks down to make simpler ones. These reactions come in the general form:

AB —> A + B

One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:

2 H2O —> 2 H2 + O2


4) Single displacement: This is when one element trades places with another element in a compound. These reactions come in the general form of:

A + BC —> AC + B

One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:

Mg + 2 H2O —> Mg(OH)2 + H2


5) Double displacement: This is when the anions and cations of two different molecules switch places, forming two entirely different compounds. These reactions are in the general form:

AB + CD —> AD + CB

One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide to form lead (II) iodide and potassium nitrate:

Pb(NO3)2 + 2 KI —> PbI2 + 2 KNO3


6) Acid-base: This is a special kind of double displacement reaction that takes place when an acid and base react with each other. The H+ ion in the acid reacts with the OH ion in the base, causing the formation of water. Generally, the product of this reaction is some ionic salt and water:

HA + BOH —> H2O + BA

One example of an acid-base reaction is the reaction of hydrobromic acid (HBr) with sodium hydroxide:

HBr + NaOH —> NaBr + H2O

SOURCE:  http://misterguch.brinkster.net/6typesofchemicalrxn.html

The ‘chemputer’ that could print out any drug | The Guardian

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When Lee Cronin learned about the concept of 3D printers, he had a brilliant idea: why not turn such a device into a universal chemistry set that could make its own drugs?

Professor Lee Cronin is a likably impatient presence, a one-man catalyst. “I just want to get stuff done fast,” he says. And: “I am a control freak in rehab.” Cronin, 39, is the leader of a world-class team of 45 researchers at Glasgow University, primarily making complex molecules. But that is not the extent of his ambition. A couple of years ago, at a TED conference, he described one goal as the creation of “inorganic life”, and went on to detail his efforts to generate “evolutionary algorithms” in inert matter. He still hopes to “create life” in the next year or two.

At the same time, one branch of that thinking has itself evolved into a new project: the notion of creating downloadable chemistry, with the ultimate aim of allowing people to “print” their own pharmaceuticals at home. Cronin’s latest TED talk asked the question: “Could we make a really cool universal chemistry set? Can we ‘app’ chemistry?” “Basically,” he tells me, in his office at the university, with half a grin, “what Apple did for music, I’d like to do for the discovery and distribution of prescription drugs.”

The idea is very much at the conception stage, but as he walks me around his labs Cronin begins to outline how that “paradigm-changing” project might progress. He has been in Scotland for 10 years and in that time he has worked hard, as any chemist worth his salt should, to get the right mix of people to produce the results he wants. Cronin’s interest has always been in complex chemicals and the origins of life. “We are pretty good at making molecules. We do a lot of self-assembly at a molecular level,” he says. “We are able to make really large molecules and I was able to get a lot of money in grants and so on for doing that.” But after a while, Cronin suggests, making complex molecules for their own sake can seem a bit limiting. He wanted to find some more life-changing applications for his team’s expertise.

A couple of years ago, Cronin was invited to an architectural seminar to discuss his work on inorganic structures. He had been looking at the way crystals grew “inorganic gardens” of tube-like structures between themselves. Among the other speakers at that conference was a man explaining the possibilities of 3D printing for conventional architectural forms. Cronin wondered if you could apply this 3D principle to structures at a molecular level. “I didn’t want to print an aeroplane, or a jaw bone,” he says. “I wanted to do chemistry.”

Cronin prides himself on his lateral thinking; his gift for chemistry came fairly late – he stumbled through comprehensive school in Ipswich and initially university – before realising a vocation for molecular chemistry that has seen him make a series of prize-winning, and fund-generating, advances in the field. He often puts his faith in counterintuition. “Confusions of ideas produce discovery,” he says. “People, researchers, always come to me and say they are pretty good at thinking outside the box and I usually think ‘yes, but it is a pretty small box’.” In analysing how to apply 3D printing to chemistry, Cronin wondered in the first instance if the essentially passive idea of a highly sophisticated form of copying from a software blueprint could be made more dynamic. In his lab, they put together a rudimentary prototype of a chemical 3D printer, which could be programmed to make basic chemical reactions to produce different molecules.

He shows me the printer, a nondescript version of the £1,200 3D printer used in the Fab@Home project, which aims to bring self-fabrication to the masses. After a bit of trial and error, Cronin’s team discovered that it could use a bathroom sealant as a material to print reaction chambers of precisely specified dimensions, connected with tubes of different lengths and diameters. After the bespoke miniature lab had set hard, the printer could then inject the system reactants, or “chemical inks”, to create sequenced reactions.

The “inks” would be simple reagents, from which more complex molecules are formed. “If I was being facetious I would say that to find your inks you would go to the periodic table: carbon, hydrogen, oxygen, and so on,” Cronin says, “but obviously you can’t handle all those substances very well, so it would have to be a bit more complex than that. If you were looking to make a sugar, for example, you would start with your set of base sugars and mix them together. When we make complex molecules in the traditional way with test tubes and flasks, we start with a smaller number of simpler molecules.” As he points out, nearly all drugs are made of carbon, hydrogen and oxygen, as well as readily available agents such as vegetable oils and paraffin. “With a printer it should be possible that with a relatively small number of inks you can make any organic molecule,” he says.

The real beauty of Cronin’s prototype system, however, is that it allows the printer not only to control the sequences and exact calibration of inks, but also to shape, from a tested blueprint, the environment in which those reactions take place. The scale and architecture of the miniature printed “lab” could be pre-programmed into software and downloaded for use with a standard set of inks. In this way, not only the combinations of reactants but also the ratios and speed at which they combine could be ingrained into the system, simply by changing the size of reaction chambers and their relation with one another; Cronin calls this “reactionware” or, because it depends on a conceptualised sequence of flow and reorientation in a 3D space, “Rubik’s Cube chemistry”.

“What we are trying to do is to combine the notion of a reaction with a reactor,” he says. “Conventionally the reactor is just the passive space or the environment in which a reaction takes place. It could be something as simple as a test tube. The printer allows it to be a far more active context.”

So far Cronin’s lab has been creating quite straightforward reaction chambers, and simple three-step sequences of reactions to “print” inorganic molecules. The next stage, also successfully demonstrated, and where things start to get interesting, is the ability to “print” catalysts into the walls of the reactionware. Much further down the line – Cronin has a gift for extrapolation – he envisages far more complex reactor environments, which would enable chemistry to be done “in the presence of a liver cell that has cancer, or a newly identified superbug”, with all the implications that might have for drug research.

In the shorter term, his team is looking at ways in which relatively simple drugs – ibuprofen is the example they are using – might be successfully produced in their 3D printer or portable “chemputer”. If that principle can be established, then the possibilities suddenly seem endless. “Imagine your printer like a refrigerator that is full of all the ingredients you might require to make any dish in Jamie Oliver’s new book,” Cronin says. “Jamie has made all those recipes in his own kitchen and validated them. If you apply that idea to making drugs, you have all your ingredients and you follow a recipe that a drug company gives you. They will have validated that recipe in their lab. And when you have downloaded it and enabled the printer to read the software it will work. The value is in the recipe, not in the manufacture. It is an app, essentially.”

What would this mean? Well for a start it would potentially democratise complex chemistry, and allow drugs not only to be distributed anywhere in the world but created at the point of need. It could reverse the trend, Cronin suggests, for ineffective counterfeit drugs (often anti-malarials or anti-retrovirals) that have flooded some markets in the developing world, by offering a cheap medicine-making platform that could validate a drug made according to the pharmaceutical company’s “software”. Crucially, it would potentially enable a greater range of drugs to be produced. “There are loads of drugs out there that aren’t available,” Cronin says, “because the population that needs them is not big enough, or not rich enough. This model changes that economy of scale; it could makes any drug cost effective.”

Not surprisingly Cronin is excited by these prospects, though he continually adds the caveat that they are still essentially at the “science fiction” stage of this process. Aside from the “personal chemputer” aspect of the idea, he is perhaps most enthused about the way the reactionware model could transform the process of drug discovery and testing. “Over time it may redefine how we make molecules,” he believes. “In particular we can think about doing complex reactions in the presence of complex chemical baggage like a cell, and at a fraction of the current cost.” Printed reactionware could vastly speed up the discovery of new proteins and even antibiotics. In contrast to existing technologies the chemical “search engine” could be combined with biological structures such as blood vessels, or pathogens, offering a way to quickly screen the effects of new molecular combinations.

After publishing some of this thinking and research in recent papers, Cronin has of course been talking to various interested parties – from pharmaceutical companies intrigued by its implications for their business models, to Nato generals responding to the idea of the ultimate portable medicine cabinet on the battlefield.

He hopes that large-scale humanitarian organisations – the Bill and Melinda Gates Foundation and the rest – might take a hard look at the public health and cost benefits of introducing such a possibly revolutionary technology to the developing world. As a scientist, Cronin tends to play down the potential legal and practical obstacles that will no doubt challenge the idea – “I don’t imagine gangsters printing their own drugs, no” he says to one question – and sees only benefits.

“As yet,” he says, “we don’t even know what the device would look like.” But he believes that now the idea is established “there is no reason at all – beyond a certain level of funding – why it all couldn’t happen very soon.” Cronin is impatient to get on with it as quickly as possible. “As well as transforming the industry and making money,” he says, “we could be saving lives. Why wait?”

SOURCE:  http://www.guardian.co.uk/science/2012/jul/21/chemputer-that-prints-out-drugs