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Tue Sep 19, 2017, 08:41 PM

"Smart Bricks" for Measuring the State of Gasifier Walls.

It is becoming increasingly clear that all efforts to address climate change have failed, and it will fall to future generations - assuming that we have not permanently impoverished them and destroyed their futures with our bad thinking on energy and the environment, left and right - to clean up the mess with which we've left them.

In desultory reading on a night of reflection on my life where I feel the guilt of my generation, the history bad ideas in energy flows before me like a suddenly honest sinner's nightmare, but even as I recognize our crime against the future, I am forced to confess that not every bad idea is totally without merit if at least something valuable can be extracted from it.

One of the worst ideas in energy - one that has actually seen, happily only in a limited number of places, industrial application - was a pet project of Jimmy Carter, he of the bad ideas in energy. Briefly, at least while a Presidential primary candidate, though thankfully not when he actually became President, this bad idea was also endorsed, in theory at least, by Barack Obama. The bad idea to which I refer is, of course, coal gasification, technically known as "reformation" to make synthetic petroleum, also known as Fischer Tropsch fuels. (I opposed Obama in the 2008 primaries based on this position; happily he proved me wrong, his policies were much superior to his rhetoric in this case.)

In coal gasification, the idea is to heat coal to very high temperatures under pressure in the presence of steam - actually not steam but supercritical water - to make a mixture of hydrogen and carbon oxides known colloquially as "Syn gas." If the heat from this process is generated by burning coal and dumping the waste indiscriminately into the air, this technology would at best double, at worst more than triple, the climate change impact of petroleum, said climate impact already being entirely unacceptable.

Because we are not smart enough, or honest enough to even stop using fossil fuels, choosing to address them instead with worthless pablum about a grand "renewable energy" future that did not come, is not here, and will not come, the engineering challenge for future generations will dwarf ours, since they will need not only to ban fossil fuels, but will also remove the hundreds of billions of tons of dangerous fossil fuel waste, carbon dioxide, from the atmosphere, where it has been accumulating at a rate of over 30 billion tons per year, a rate which is rising, not falling, mostly because of the runaway popularity of the dangerous fossil fuel natural gas for which so called “renewable energy” is nothing more than a fig leaf. (Dangerous natural gas is not clean; it is not safe, and in spite of tiresome and obviously untrue nonsense put out by purveyors of the grotesquely failed and ridiculously expensive so called “renewable energy” scam, it is not “transitional.”)

Sophisticated arguments have been made that the thermodynamic and thus the related economic engineering challenges of removing carbon dioxide from the atmosphere make it next to impossible. A widely discussed paper on this topic is here:

Economic and energetic analysis of capturing CO2 from ambient air (House et al , PNAS.108 51 20428-20433.(2011)]

A number of arguments questioning this assumption have been advanced and, in the very same journal where the House paper was published, a team of scientists at Columbia has argued in an overview paper that House's paper better not be the last word because removing the dangerous fossil fuel waste carbon dioxide is an urgent matter: The urgency of the development of CO2 capture from ambient air (Lackner et al, PNAS 109 13156–13162 (2012)) Of course, this paper was published, as of this writing, almost 5 years ago, so whatever “urgency” there is about climate change, it’s been totally ignored, which is not to say it's really not urgent, only that it's becoming more urgent.

For a nice review of chemical air capture strategies see: Direct Capture of CO2 from Ambient Air (Jones et al Chem. Rev., 2016, 116 (19), pp 11840–11876) (I've attended lectures by the primary author of this review, Chris Jones, of Georgia Tech, at scientific meetings; I'm impressed by his work.)

From my perspective, air capture should be an achievable goal for human beings in a generation less stupid and selfish than ours. I say this only because clearly plants do this (albeit surprisingly inefficiently in energy to mass ratio terms) and therefore, just as generations of human beings living before the Wright brothers recognized that heavier than air flight had to be possible, since birds and insects existed. House's paper explicitly states that biological strategies for removing carbon dioxide are not covered.

There is, of course, an option that simultaneously exploits both biological and physicochemical options for removing carbon dioxide from the atmosphere, and utilizes chemistry that I evoked at the outset of this post, reformation, not of coal, but of biomass. The combustion of biomass has been, or course, practiced for millennia, and it is still practiced widely today; but as practiced it is very dangerous, dangerous biomass waste is responsible for about half of the seven million air pollution deaths that take place each year as of 2017, even as awful poorly educated dullards carry on about so called “nuclear waste,” which has killed no one in more a half a century of accumulation, and which is in actuality a valuable resource that future generations may appreciate more than most people in this entirely easily distracted generation are competent to understand.

No matter.

My hostility to so called “renewable energy” should be familiar to anyone familiar with my writings here and elsewhere, and biomass is often defined as “renewable energy” but, this said, I believe, as I do for so called “nuclear waste,” that biomass waste has great potential as a resource, most notably for the removal of carbon dioxide from the atmosphere, but also for the recovery of other critical materials, the most important of which is phosphorous. (World supplies of mineable phosphorous – on which the world’s food supply currently depends – are very much subject to depletion.)

While “renewable” biofuels like ethanol have represented a tremendous environmental tragedy in the United States, (you know, the road to hell…) resulting in the destruction of the Mississippi Delta ecosystem, for example, it happens that there is another approach to biomass utilization that is likely to prove far more benign than fermentation and distillation, and to the extent it is one of the few options capable of actually removing carbon dioxide from the air, deserves consideration. This is the thermal reformation of biomass, where biomass substitutes for the coal based scheme that Jimmy Carter proposed, and which frankly, we should all be grateful, never made it to big time in the United States, the world’s most egregious consumer nation.

If the heat for driving this largely endothermic reaction is nuclear heat, the process is almost certain to be unambiguously carbon negative, particular in the case where the carbon collected is utilized in products like polymers, carbon fibers, carbon nanotubes, refractory metal carbides (which would be necessary for nuclear heat at high enough temperatures to drive reformation reactions and thermochemical water splitting reactions), silicon carbides and extremely useful and exciting graphene, modified graphene and carbon nitrides. All of these products sequester carbon, and do so in an economically viable way, a “waste to products” way.

But there’s a problem. Biomass is not pure carbon, hydrogen, oxygen and nitrogen, of course: It also contains a considerable fraction of metals. The most problematic of these are the alkali metals, in particular potassium and sodium, and to a far lesser extent, lithium and rubidium.

Consider potassium.

A nice paper, the residue of Chinese grammar in the translation aside, which was recently released as a corrected proof discusses the case quite well: Transformation and release of potassium during fixed-bed pyrolysis of biomass (Lei Deng Jiaming Ye Xi Jin Defu Che, Journal of the Energy Institute, Corrected Proof, Accessed 9/19/17)

An excerpt:

In China, a few biomass-fired boilers have been successively built and operated during last ten years [8], and grate firing is still the most widely used firing method. However, the grate-fired boiler has been experiencing serious problems of fouling, slagging and high-temperature corrosion according to the foreign experiences [6,9e12]. In China, although the operational time of the grate-fired boiler was relatively short, the tube bursting of superheaters began to occur due to the deposit-induced high-temperature corrosion [13e16]. These problems appeared in biomass-fired boilers have been considered to originate from the release of K, Cl and S during combustion of biomass.

The occurrences of ash deposition and high-temperature corrosion on superheaters have experienced three processes. First, parts of K, Cl and S go into the gas phase to form HCl, Cl2, SO2, SO3, KOH, KCl or K2SO4 during combustion of biomass [7,17e19]. Second, gaseous potassium salts condense in the gas phase and on the surface of superheater to form sticky particles and condensed layer, respectively. Then the ash deposition occurs when fly ash particles are trapped by the sticky condensed layer [9e11,16]. Finally, the ash deposit (mainly composed of KCl and K2SO4) and metallic matrix react with HCl, Cl2, SO2 or SO3, which would cause the growth of ash deposit and high-temperature corrosion [9,12,20e23]. Obviously, potassium is involved in all three processes and plays a crucial role. Compared with coal, biomass generally has much higher potassium content [5,24]. Although pyrolysis is different from combustion with regard to the surrounding environment and temperature fields, it is still meaningful to investigate the transformation and release of potassium during biomass pyrolysis, because pyrolysis happens at the primary stage of combustion. The investigation will be significantly helpful to understand the origin of ash deposition and high-temperature corrosion occurred on superheaters and find methods to solve these problems. It can also be useful to the design of biomass-fired boilers or other thermal conversion equipment.

A form of energy technology which requires constant replacement of infrastructure is neither sustainable nor environmentally benign, simply from a materials utilization standpoint, since the preparation of materials is generally energy intensive. (This is a big problem with another example of the failed expensive so called "renewable energy" industry, the wind industry, where Danish database of turbines shows that the piece of crap turbines don't last an average of 16 years before needing replacement.)

I personally believe that the materials science issues involved of high pressure reformers is one that can be solved; however the question stands unequivocally before us that we are out of time, that anything we may or may not do to address climate change is already too late. It may be desirable therefore to build less than optimized biomass reformers, at least as a stopgap measure, until engineers and scientists can optimize materials to be more sustainable. We must have technologies that not only prevent the dumping of dangerous fossil fuel waste into our favorite waste dump, the planetary atmosphere, but also remediate the waste dump itself: Our atmosphere is a "superfund" site, and we must find a way to clean it.

It is therefore with interest that I read a recently published paper that purports to have developed a technology that can at least measure the performance of materials in high temperature reformers continuously, during operation.

The paper is here: Estimations of Gasifier Wall Temperature and Extent of Slag Penetration Using a Refractory Brick with Embedded Sensors (Debangsu Bhattacharyya, et alInd. Eng. Chem. Res., 2017, 56 (35), pp 9858–9867)

Some text from the paper:

Integrated gasification combined cycle (IGCC) technology is a promising technology for producing electricity from fossil fuels and biomass with high efficiency. This technology offers superior environmental performance and high energy efficiency. 1,2 The gasifier is the heart of IGCC plant.3−5 The operating temperature of a gasifier is one of the key variables.6,7 Lower temperature can lead to lower carbon conversion and increase the viscosity of slag, eventually leading to disruption in the slag flow.8 Higher operating temperature can improve carbon conversion but reduces the life of the refractory.9,10 The lifetime of the refractory lining of the gasifier is a major concern for both cost11 and availability. If the gasifier is operated at the optimum temperature, the lifetime of the high chromia refractory can be prolonged to almost 2 years.10,12 Therefore, it is desired that the operating temperature of a gasifier is strictly monitored and controlled.

"Almost two years..." That's even worse than wind turbines, and wind turbines suck. Moreover, the liner they're describing is chromia. Chromium is not an environmentally benign element with which to work. (To be fair there are many other refractory oxides, carbides and nitrides with which one can envision accomplishing the same task, one of the most important of these is zirconia, ZrO2, and of course nitrides, like, say, thorium nitride.

The authors go on in the paper to describe a type of brick with an embedded sensor. The brick is alumina and in it is embedded a thermoresistor made of tungsten carbide in an alumina matrix.

The sensor is arranged so as to give an interdigital capacitor, a set of capacitors in series that measure changes in temperature via changes in the diaelectric constant of the system and thermal expansion resulting in changes in distance between the capacitor as well as changes in the diaelectric constant (presumably from a base line) owing to the intrusion of slag elements.

Some remarks from the conclusion:

In this paper, a rigorous, first-principles, dynamic model of the smart refractory brick has been developed. The thermal model for multilayer gasifier wall has been developed by considering properties of the pristine smart refractory brick as well as that of the slag-infiltrated brick. Models of the interdigitated capacitor as well as the thermistor have been developed by considering the installation direction and the geometries of the embedded sensors. Using the TKF, both the thermistor and IDC sensors are found to provide satisfactory estimates of the temperature profile for pristine and slag-infiltrated bricks despite high model mismatch. Our results show that satisfactory estimation of temperature profile can be obtained even for locations where there is no sensor by utilizing measurements from sensors placed elsewhere. This suggests that an optimal sensor placement would be very valuable for these smart bricks. The TKF is found to result in poor estimation of the slag penetration length. However, the EKF yields superior estimates even though the rate of change of the capacitance becomes higher when the slag reaches the sensor...

...For commercial application of the smart refractory brick in industrial gasifiers, many aspects need to be investigated. First, the brick needs to be tested under actual operating conditions for prolonged time. Second, impacts of the startup/shutdown and off-design operating conditions on the brick stability need to be evaluated. Third, response of the embedded sensors may be affected by unknown inputs. Fourth, because a wireless transmission system is being considered, there may be issues due to communication constraints, packet dropouts, and synchronization errors. The authors look forward to investigating some of these aspects in the near future.

One wishes the authors luck in a country, this one, where the three branches of government are controlled by people who hate science because they're too stupid to know any.

I appreciate the work of Dr. Debangsu Bhattacharyya, as well as his courage to bear his very cool name right in the heart of Trump country, West Virginia.

Interesting work.

Enjoy the rest of the work week.

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