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Incinerating Lawn Mower

Lighter Loads for Lawn Lovers
  (+4, -1)
(+4, -1)
  [vote for,

Mowing during wet days or even heavy downpour has never been pleasant. But there are always solutions to problems!

This lawn mower has two intermeshed spinning cylindrical mower blades, featuring opposing action. Grass is thrown upwards into a bisected, spinning toroidal structure with a mesh bottom, covered with a dome and a two meter tall stack on the top.

As the grass lands on the mesh, it is roasted over gas flames. As the grass roasts in the central area; steam goes up the stack and over the user, and ash goes out to the sides, caught in a secondary ash catcher protected from the rain and deposited in a flexible silicone bag dangling from the handles like most mower bags do; OR thrown to either side of the mower to fertilize the lawn.

It also comes with a switch to run in reverse, delivering scorching air to your grass to kill and wither the hardiest weeds.

mylodon, May 25 2023

Lawnmower Man https://en.wikipedi...i/The_Lawnmower_Man
Had his own way of disposing of … clippings [a1, May 25 2023]

Grass heating values https://bioresource...emical-composition/
[daseva, May 26 2023]


Voice, May 25 2023

       Nice. It makes one think about a grass gasifier where the lawn itself provides the fuel for its own mowing.   

       That would make a compelling horror movie for an audience of grass.
pertinax, May 25 2023

       Field Of Dreams.   

       A mini version would make a good hair shaver for delivering No 1s, 2s, 3s & 4s.
xenzag, May 25 2023

       The whole blades thing sounds very slow and inefficient. Can't there be some quicker solution using shaped charges?
pocmloc, May 25 2023

       // a compelling horror movie //   

       Lawnmower Man. But just the 1975 short story by Stephen King (link). Not the 1992 movie - which was so bad that King sued to have his name taken off of the project.
a1, May 25 2023

       The 'deluxe' model supplies the lawnmower operator with tasty barbecued snacks.
hippo, May 25 2023


       And if the unit is run in reverse the entire time, no more lawn.
whatrock, May 25 2023

       1) What does the grass being wet have to do with this?   

       2) I'm sure your neighbors will be thrilled with you blowing smoke all over the place.   

       3) Have you SEEN the cost of gas lately?   

       4) That 2 meter stack on top is going to hamper your mobility more than I think you realize, making maneuvering around the shed/garage difficult, as well as making it impossible to mow in hard to reach places like under lawn tables, porches, etc.   

       5) Back to the 'wet' thing... mowing while it's raining isn't just unpleasant; it's a bad idea. The grass being wet dulls your blade quicker, puts more strain on the moving parts, shortening the life of the mower, and because of the extra weight on the grass, causes your mower to miss more with each pass. But again... what does it have to do with the idea?
21 Quest, May 26 2023

       (1) Fire is antithetical to wetness.   

       (2) Residential burn permits are common. They will live.   

       (3) Can you really "see" the cost of anything?   

       (4) Put it on a gyro to keep it balanced, like those cruise ship pool tables, and built out of telescoping sections. Obviously.   

       (5) You seem to have glossed over the bisected, spinning toroidal structure. This will undoubtably create the lift necessary to resurrect the limp blades of grass to their day of reckoning.
daseva, May 26 2023

       //It makes one think about a grass gasifier where the lawn itself provides the fuel for its own mowing.//   

       The energetic cost of evaporating the water content of the grass clippings is the barrier here, you have to do that to completion before you can start thermally degrading the cellulose etc.
bs0u0155, May 26 2023

       If I weedwack grass and let it sit for a few hours in the sun, and then mow with a bag, my bags hold more. Now, it's a lot of weedwhacking and time management, but I can fit more in my green waste. Ideally it would ashify but even a partially drying version would be beneficial
mylodon, May 26 2023

       Some common grasses release about 18 kJ/g (linky). Water has a heat of vaporization around 2 kJ/g. With a heat capacity of 4 J/g*C we can estimate it will take ~ .3 kJ/g to heat water from 20 dec C to boiling. So, 2.3 kJ/g to get rid of the water. Assuming the grass/water mass ratio is 1 for a very wet grass (just spitballing this one), we will get a surplus of heat ~ 15 kJ/g with 100% heat transfer efficiency. Of course, this will not be achievable, but it indicates some level of moisture may not be an impossible barrier with the right ignition conditions and chamber design.
daseva, May 26 2023

       //The energetic cost of evaporating the water content of the grass clippings is the barrier here, you have to do that to completion before you can start thermally degrading the cellulose etc.//   

       I'd thought to use last weeks cuttings to fuel next weeks mowing.
Sure you have to cut it rake it and haul it old-school the first week, but every week after that is free fuel. Maybe use prunings for the first mow.

       <off topic>
Why is 'prunings' tagged as a misspelling on this site?

       If the grass isn't burning there isn't enough oxygen present. Try lox. Or ammonium nitrate.
Voice, May 27 2023

       I'm not convinced ammonium nitrate would promote the burning of the grass; it would be more likely to just scatter it over a wide area, wouldn't it?   

       Perhaps thermite was what you wanted?
pertinax, May 27 2023

       Controlled high temperature decomposition of ammonium nitrate?
Voice, May 29 2023

       I'm greedy; I want to keep *all* my fingers.
pertinax, May 29 2023

       Well controlled decomposition. You pansy.
Voice, May 29 2023

       Okay, so it looks like hydrogen peroxide would be far more efficient, even if it is less exciting.
Voice, May 29 2023


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