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US 2009/0214395 A1Published application
Raw Material Efficiency Method and Process
AssigneeThe Dow Chemical Company
InventorsJohn R. Parrish, Jeffrey B. Drabish, Oscar M. Longoria, JR., James L. Swecker, II
Life of this patent
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Abstract
A method and apparatus are disclosed for controlling product discharge from a fluidized bed reactor and for minimizing the loss of the unreacted monomer in the fluidizing gas upon removing the solid polymer product from the reactor. The method and apparatus utilize at least one detector in the product tank or its vent line and a control system in communication with the detector and the product tank fill valve, along with certain algorithms, to adjust by an iterative process, the product discharge time, thereby maximizing resin fill in the product tank and minimizing the lost reactor gas volume.
Claims29
A method of removing a solid particulate product from a fluidized bed reactor, the method comprising:
- (a) providing:
- (i) a product tank connected with a fluidized bed reactor through a fill valve and comprising a means for emptying and a means for venting;
- (ii) a detector that provides a response when a solid particulate product fills or overfills the product tank to the level of the detector;
- and
- (iii) a control system in communication with the detector and the fill valve and capable of controlling the fill valve;
- (b) performing at least one discharge cycle comprising:
- (i) opening the fill valve for a pre-determined time period and transferring the solid particulate product together with gas from the fluidized bed reactor into the product tank;
- and
- (ii) after the pre-determined time period, closing the fill valve and emptying the product tank;
- (c) while performing step (b), calculating a desired adjustment to the pre-determined time period using a control algorithm and at least one detector response or absence thereof obtained while performing at least one discharge cycle;
- and
- (d) adjusting the pre-determined time period by the desired adjustment using the control system.
9 more elements
A method of removing a solid particulate product from a fluidized bed reactor, the method comprising:
- (a) providing:
- (i) a product tank connected with a fluidized bed reactor through a fill valve and comprising a means for emptying and a means for venting;
- (ii) a first detector that provides a response when a solid particulate product fills or overfills the product tank to a first level;
- (iii) a second detector that provides a response when a solid particulate product fills or overfills the product tank to a second level which is higher than the first level;
- and
- (iv) a control system in communication with the detector and the fill valve and capable of controlling the fill valve;
- (b) performing at least one discharge cycle comprising:
- (i) opening the fill valve for a pre-determined time period and transferring the solid particulate product together with gas from the fluidized bed reactor into the product tank;
- and
- (ii) after the pre-determined time period, closing the fill valve and emptying the product tank;
- (c) while performing step (b), calculating a desired adjustment to the pre-determined time period using a control algorithm and at least one detector response or absence thereof from the first detector, the second detector, or both, obtained while performing at least one discharge cycle;
- and
- (d) adjusting the pre-determined time period by the desired adjustment using the control system.
10 more elements
A method of removing a solid particulate product from a fluidized bed reactor, the method comprising:
- (a) providing multiple parallel series of tanks comprising a first product tank, a first blow tank, a second product tank, and a second blow tank, wherein:
- (i) each product tank is connected with the fluidized bed reactor through a fill valve and comprises a means for emptying and a means for venting;
- (ii) a detector is provided for each product tank to provide a response when a solid particulate product fills or overfills the product tank to the level of the detector;
- and
- (iii) a control system is provided for each product tank in communication with the detector and the fill valve and capable of controlling the fill valve;
- (b) for one parallel series of tanks, transferring the solid particulate product together with the gas from the reactor into the first product tank by:
- (i) opening the fill valve for a pre-determined time period and transferring the solid particulate product together with gas from the fluidized bed reactor into the first product tank;
- (ii) after the pre-determined time period, closing the fill valve and emptying the first product tank;
- (c) while performing (b), transferring solid particulate product from the second product tank to the second blow tank;
- (d) while performing (b) and (c), transferring solid particulate product from the first blow tank to a further destination having a pressure lower than the first blow tank;
- (e) after performing (b), (c), and (d), passing gas from the first product tank to the second product tank;
- (f) passing gas from the second blow tank to the first blow tank;
- wherein each of (b), (c), (d), (e), and (f) are isolated by closed valves from any of the reactor, the product tanks, and the blow tanks not necessary for the performance thereof;
- (g) repeating steps (b)-(f) for each remaining parallel series of tanks;
- (h) repeating steps (b)-(g) any number of times and for each product tank independently calculating a desired adjustment to the pre-determined time period using a control algorithm and at least one detector response or absence thereof for that product tank, obtained while performing step (b) for that product tank;
- and
- (i) adjusting the pre-determined time period for each product tank independently by the desired adjustment using the control system.
14 more elements
Dependencies are inferred from the claim text.