BURNER NOZZLE WITH BACKFLOW PREVENTION FOR A FLUIDIZED BED BIOGASIFIER
A fluidized bed biogasifier is provided for gasifying biosolids. A feeder feeds biosolids into a reactor vessel at a desired feed rate during steady-state operation. A fluidized bed in the base of the reactor vessel has a cross-sectional area that is proportional to at least the fuel feed rate such that the superficial velocity of gas is in the range of 0.1 m/s to 3 m/s. The biosolids are heated inside the fluidized bed reactor to a temperature range between 900° F. and 1700° F. in an oxygen-starved environment having a sub stoichiometric oxygen level, whereby the biosolids are gasified. A burner system having a hooded nozzle below the fluidized bed in the reactor vessel provides high temperature gas to the biogasifier.
1 - 9 . (canceled)
10 . A method for gasifying biosolids comprising the steps of:
feeding biosolids in a fluidized bed biogasifier, the biogasifier having:
a reactor vessel;
a freeboard section of said reactor vessel;
a feeder for feeding biosolids into said reactor vessel, said feeder being configured to feed said biosolids into said reactor vessel at a biosolids fuel feed rate during steady-state operation of the biogasifier; and
a fluidized bed in a bed section of said reactor vessel;
wherein the freeboard section has a greater diameter than the fluidized bed;
providing gas to said fluidized bed; and
heating and reacting said biosolids inside said biogasifier, whereby biosolids are gasified.
11 . The method of claim 10 , wherein the step of providing gas to said fluidized bed comprises providing high temperature gas below the fluidized bed.
12 . The method of claim 10 , wherein the step of providing gas to said fluidized bed comprises providing high temperature gas through a nozzle, where the nozzle is below the fluidized bed.
13 . The method of claim 12 , wherein the nozzle includes a hood, where the hood restricts solids from flowing into the nozzle.
14 . The method of claim 12 , further comprising the step of providing additional fluidizing gas into the reactor vessel, where the additional fluidizing gas is recycled flue gas.
15 . The method of claim 10 , wherein the freeboard has a diameter of at least 57 inches.
16 . The method of claim 10 , where there is a temperature within the reactor vessel, wherein the method further comprises the step of adjusting the temperature within the reactor vessel by adjusting a rate at which oxidant gas is provided to the reactor vessel.
17 . The method of claim 10 , wherein the bed section has a height and a media bed depth, where the height of the bed section is 1.5 times the media bed depth.
18 . A biogasifier comprising
a reactor vessel having a freeboard section and a bed section, where the bed section is below the freeboard section, where the bed section has a fluidized bed;
a burner system having a nozzle, where the nozzle is below the bed section, where the burner system provides heated gas to the reactor vessel.
19 . The biogasifier of claim 18 , further comprising a hood, where the hood is secured to the nozzle, and where the hood restricts solids from flowing into the nozzle.
20 . The biogasifier of claim 18 , wherein the hood is welded to the nozzle.
21 . The biogasifier of claim 18 , wherein the hood comprises stainless steel.
22 . The biogasifier of claim 18 , wherein the nozzle is a slot in a pipe.
23 . A method of gasifying a biosolid comprising the steps of:
providing biosolids into a reactor with a fluidized bed;
providing a heated gas to the reactor from below the fluidized bed;
waiting until the fluidized bed reaches a minimum threshold temperature and then providing additional fluidizing gas into the reactor;
removing flue gas from the reactor; and
passing flue gas removed from the reactor through a heat exchanger.
24 . The method of claim 23 , wherein the heated gas is provided to the reactor through a nozzle.
25 . The method of claim 24 , wherein the nozzle comprises a hood, where the hood restricts solids from flowing into the nozzle.
26 . The method of claim 23 , wherein the minimum threshold temperature is 900° F.
27 . The method of claim 23 , further comprising step of adjusting a temperature in the reactor by adjusting amount of oxidant gas entering into the reactor.
28 . The method of claim 23 , wherein the additional fluidizing gas comprises flue gas previously removed from the reactor.
29 . The method of claim 23 , wherein the heat exchanger transfers heat from flue gas removed from the reactor to the additional fluidizing gas before it is provided into the reactor.
30 . The method of claim 23 , further comprising the step of transferring heat from the heat exchanger to sludge to form dried sludge, wherein the biosolids provided into the reactor comprise the dried sludge.