Fluidized bed reactor

Fluidized bed reactor (FBR)

Fluidized bed reactor (FBR) are chambers that allow the mixing of liquid or gas substrates with powdered catalysts such that the catalyst acts like a fluid, maximizing mixing and catalyst action. The basic configuration is detailed to the right where a substrate is passed upward through the chamber under pressure through a plate that supports the catalyst. FBRs are essential production of many materials and chemicals and is needed for several basic capabilities of the GVCS.

FBR for bioplastic production

As part of the OSE product ecology a reactor that could be used for ethanol dehydration and ethylene polymerization is a proposed route to locally produced renewable bioplastic. Due to the nature of the subtrates, powdered catalysts, and optimal catalytic conditions FBRs have demonstrate superior performance with high process reactivity and selectivity.

Defining the machine requirements:

1. Reactor chamber with ability to add or remove substrate, product, catalyst, gases, and control temperature, pressure, and the speed which substrate moves through the reactor. a. Dimensions based on reaction volume? b. Hoppers would have to be of adequate size to benefit reaction volume

2. Safety: able to withstand heat and pressure, dangerous chemicals kept behind two layers of protection, product handled with precautions a. reactor materials b. design for longterm quality

3. Recycling of unused substrate, carrier gas, catalyst. a. Catalyst regenerator to autoclave and activate used up catalyst.

4. Saving thermal energy: isothermal or adiabatic, heat catalyst and substrate with steam depending on moisture requirements

5. Control of atmosphere: gas content, increased and decreased pressure ranges, gas content in the reactor and downstream, gas mixture controls upstream

6. Control and interface: sensors of pertinent conditions and an easy to understand display of the conditions, controls over conditions and inputs and outputs

Literature and patent review

US patent 4,003,712 issued to Miller on Jan. 18, 1977 details a fluid bed reactor for use in a olefin polymerization.

US patent 4,003,712

The reactor contains a reaction zone 12 where substrate and catalyst are combined. The substrate is supported by a fluid bed which allows the injection of substrate which allows maximum mixing due to the fluid like behavior of the catalyst. Unused substrate, catalyst, and carrier gas can be recycled through the system. Above the reaction zone is a slow down zone 14 where products collect and are sorted. Gas collects the velocity reduction zone and recycle gas is collected through the a line at the top of the zone. An optional cyclone 22 can aid in gas collection and a filter 24 catches small particles. A heat exchanger 26 acts to recycle heat and maintain the system at a constant temperature and the gas is compressed by a compressor 28. New catalyst can be added through input 30 with a proper gas mixture and preheated, reserve catalyst is held in nitrogen in 32.

A reactor device detailed in U.S. patent 4,134,926 belonging to Tsao and Zasloff issued Jan 6 1979 utilizes a fluid bed reactor (11) to catalyzed the reaction of ethanol dehydration.

US patent 4,134,926

The reactor contains powdered catalyst supported on a distributor which can dispense feed ethanol through the catalyst. Ethanol is passed through the distributor in gas phase at 750 C into the reactor chamber at the same temperature. The catalyzed reaction takes place on the surface of the catalyst powder, and the product escapes as gas. The product is equal parts water and ethylene. Catalyst may be removed and loaded into reactor using hopper chambers, which offer the advantage of preparing the new catalyst to ideal temperature and conditions increasing control of the main reactors conditions. According to the patent ethylene yields of 99% are possible with fluidized bed reactors.

US patent 4,383,095 issued to Goeke on May 10 1983 details a high activity catalyst and a the operation of the fluid bed reactor for its use. The FBR adds activator compounds at the hottest point of the gas recycle line which would be downstream of the compressor and before the heat exchanger?, however the patent calls for placement downstream of the heat exchanger.

US patent 5,028,670 issued to Chinhe and Dumain on July 1, 1991 details a fluid bed reactor configured for olefin polymerization so as to avoid fouling by particles carried into the gas recycle line.

US patent 5,028,670

A liquid vapor separation The device utilizes two heat exchangers in the gas recycle line downstream.

Proposed plan of action

1. COnstruction of simple small (laboratory) scale reactor that may or may not incorporate ability to remove and reload catalyst or recycle gases.

2. Demonstration of reactors capabilities to catalyze ethanol dehydration and ethylene polymerization using purchased catalysts and substrates. Successful creation of polyethylene will demonstrate the ability to conduct the process on a small scale.

3. Construction of second generation reactor that incorporates more advanced loading and unloading abilities and environmental controls that can operate in continuous mode.

4. Testing of reactor and utilization in other catalyst reactions under different conditions than bioplastic reactions.

5. Construction of full scale reactor capable of supporting village sized population with ability to load multiple substrates, catalyst hopper, gas control and recycling, and which can be operated in extended continuous for long periods and rapidly reconfigured.

6. Demonstration of industrial standard open source fluid bed reactor in a variety of applications.

Links

http://en.wikipedia.org/wiki/Fluidized_bed_reactor

http://www.fischer-tropsch.org/Bureau_of_Mines/ri/ri_6209/ri_6209.pdf