Filtration system

Claim 2

A filtration system according to claim 1, including an inlet conduit for said process fluid, an outlet conduit for said backwash fluid and an entrance conduit leading from said housing, a valve connected between said entrance conduit and said process fluid inlet conduit and said backwash fluid outlet conduit for alternatively connecting same to said entrance conduiT, and a further valve connected between said backwash fluid outlet conduit and said recovery system.

Claim 3

A filtration system according to claim 3, in which said recovery system contains a valve for alternatively directing fluid flowing therethrough into a filter vessel for recycling the process fluid to the filtration system or to discharge same from the filtration system.

Claim 4

A filtration system according to claim 1 including a plurality of housings each having a filter medium therein and each having a second outlet, said recovery system including a recovery header, a plurality of valves connecting corresponding ones of said second outlets to said recovery header, said recovery system further including a filter vessel and means connecting same to said recovery header for removing large particles from residual process fluid recovered from said plurality of housings prior to backwashing.

Claim 5

In a filtration system comprising a closed housing having a first conduit at one end thereof, a second conduit at the opposite end thereof, a filter medium disposed in said housing between said ends thereof, a process liquid inlet and a backwash liquid outlet and first valve means for alternatively connecting said process liquid inlet and backwash liquid outlet to said first conduit, a process liquid outlet and a backwash liquid inlet and second valve means for alternatively connecting said process liquid outlet and said backwash liquid inlet to said second conduit, the improvement comprising recovering means for forcibly removing and recovering residual process liquid from said housing following a filtration step and prior to a backwashing step, so as to avoid cross-contamination of said residual process liquid and backwashing liquid, said recovering means including a pressure gas inlet connected to said second conduit for pressurizing said housing and a recovery system connectible to said first conduit for receiving residual process liquid driven from said housing by said gas, said first valve means including a first three-way valve connected between said process liquid inlet and said backwash liquid outlet for alternately connecting same to said first conduit, said backwash liquid outlet including a discharge conduit adjacent said first valve, a second three-way valve in said discharge conduit and alternately connectible to said recovery system and a backwash liquid receiver, said second valve means comprising a third three-way valve connected between said process liquid outlet and said backwash liquid inlet for alternately connecting same to said second conduit, said pressure gas inlet comprising a compressed gas supply conduit including a valve and connected to said backwash liquid inlet, said gas supply conduit being separated from the outlet path of said process liquid by said third three-way valve, and an air breaker valve on said backwash inlet conduit adjacent said gas supply conduit openable at the end of a backwash cycle to place the filter unit in communication with the atmosphere, whereby residual process liquid remaining in the housing after a filtration step is forcibly purged from the housing and recovered for future use before backwash liquid is introduced into the housing.

Claim 6

In a filtration system comprising a closed housing having a first conduit at one end thereof, a second conduit at the opposite end thereof, a filter medium disposed in said housing between said ends thereof, a process liquid inlet and a backwash liquid outlet and first valve means for alternatively connecting said process liquid inlet and backwash liquid outlet to said first conduit, a process liquid outlet and a backwash liquid inlet and second valve means for alternatively connecting said process liquid outlet and said backwash liquid inlet to said second conduit, the improvement comprising recovering means for forcibly removing and recovering residual process liquid from said housing following a filtration step and prior to a backwashing step, so as to avoid cross-contamination of said resIdual process liquid and backwashing liquid, said recovering means including a pressure gas inlet connected to said second conduit for pressurizing said housing and a recovery system connectible to said first conduit for receiving residual process liquid driven from said housing by said gas, said second valve means comprising a three-way valve connected between said process liquid outlet and said backwash liquid inlet for alternatively connecting same to said second conduit, said pressure gas inlet comprising a valved compressed gas supply conduit connected to said back wash liquid inlet and separated from the outlet path of said process liquid by said three-way valve, whereby residual process liquid remaining in the housing after a filtration step is forcibly purged from the housing and recovered for future use before backwash liquid is introduced into the housing.

Claim 7

Improvement in a filtration system according to claim 7, in which said first valve means includes a second three-way valve connected between said process liquid inlet and said backwash liquid outlet for alternatively connecting same to said first conduit, said backwash liquid outlet including a discharge conduit adjacent said first valve, a third three-way valve in said discharge conduit and alternately connectible to said recovery system and a backwash liquid receiver, said recovery system having a fourth three-way valve for alternatively directing residual process liquid into a recycle vessel and to drain.

Claim 8

Improvement according to claim 8, in which the recovery system includes gravity filter means for removing large solids between said third and fourth three-way valves.

Claim 9

Improvement according to claim 8, in which the recovery system includes gravity filter means for removing large solids between said fourth three-way valve and said recycle vessel.

Claim 10

Improvement according to claim 8, in which a series of closed housings having filter mediums therein are connected in parallel, said third three-way valves for all of said housings being connected by short conduits to a common recovery header which communicates with a single fourth three-way valve.

Claim 11

Improvement according to claim 7, in which said housing is tubular and has a tubular filter element therein, a vibrating device mounted in said housing outside of said tubular filter element and releasable couplings between said housing and said first and second conduits.

Claim 12

A filtering method comprising the steps of (1) during a filtration cycle, flowing a process fluid to be filtered in a first direction through a housing having a filter medium therein in order to remove unwanted particles from the process fluid, (2) at the end of the filtration cycle, terminating flow of the process fluid by adjusting a first valve to disconnect the inlet of the housing from the supply conduit for the process fluid and connecting said inlet to a drain system, leaving free residual process fluid in the housing, (3) injecting gas under pressure into said housing in the reverse direction and forcibly driving said free residual process fluid from said housing in said reverse direction so that the housing is empty of process fluid by adjusting a second valve to disconnect the outlet of the housing from the outlet conduit for the process fluid and connecting same to an inlet conduit for said gas and backwash fluid and then by admitting said gas to said inlet conduit (4) recovering said residual process fluid for reuse by discharging said residual process fluid retained in said housing through a further valve in said drain system to a recovery system while preventing said backwash fluid from entering said inlet conduit, (5) then flowing a backwash fluid through said housing in said reverse direction in order to remove contaminate from said filter element and discharging the backwash liquid and contaminate particles entrained therein from the housing so that housing is empty of backwash fluid, and (6) then reintroducing process fluid intO the housing for repeating the filtration cycle whereby contact and cross-contamination between process and backwash fluids in and adjacent the housing is substantially eliminated.

Claim 13

A filtering method according to claim 13 in which the process fluid is a slurry and the step of recovering said residual process fluid includes screening same to remove particles sized larger than solids normally in the process fluid therefrom prior to reintroducing said residual process fluid into the filtering system.

Claim 14

A filtering method according to claim 13, including the further step of flowing backwash liquid through the recovery system at selected intervals to purge process fluid therefrom and then discharging said backwash fluid from the recovery system.

Claim 15

A filtering method according to claim 13, including the step of venting said housing to the atmosphere following backwashing while draining the housing of residual backwash fluid so as to remove all backwash fluid from the housing.

Claim 16

A filtering method according to claim 16, in which the filtered process fluid is a high viscosity slurry of high solids content, the backwashing fluid is water and the gas is air.