Abstract: The present invention provides for passive V0C recovery in the fermentation process that does not affect or minimally affects the conditions within the fermentor vessel and does not affect or minimally affects the conditions within the headspace of the fermentor vessel itself while using the production of CO2 emitted during the fermenting process as the source of driving energy to move a portion of the gaseous/vaporous material in the headspace of the fermentor through an appropriately sized conduit to a chilled surface condensing device to condense the V0Cs (principally ethanol) for recovery and to exhaust the CO2 to the atmosphere or to recover the CO2 for other uses.

Abstract: A grit removal system for tanks with a need to remove settled solids (e.g., anaerobic digester tank) is described. The system is especially suitable for a large tank, preferably having a flat floor, and it works well while submerged under a liquid. Specifically, a periphery-driven rack & pinion mechanism drives a shaft to rotate about a center pivot, and scrapes settled solids towards tank periphery, where the solids fall into a pit on the tank floor. A drainage opening inside the pit, when opened by a valve, is used to flush out the solids through a standpipe into a settlement tank for final dewatering and solid disposal. The system is compatible for continuous tank operation, and is useful for stirring tanks requiring periodic sediment removal.

Abstract: The improved circular secondary clarifier of the present invention requires less surface area and low HRT and provides efficient solids-liquid separation. The improved clarifier has better SS and BOD reduction and provides high under flow solids concentrations, as compared to conventional secondary clarifiers. The improved clarifier is even capable of treating wastewaters containing low MLSS concentration. One of the biggest advantages of improved clarifier is that it does not require a separate sump cum pump house as it removes the settled sludge using suction mechanism thereby reduces capital and recurring cost. Further, it provides natural flocculation, which is essential for agglomeration of solids and increases particle size referred to as ‘floc’ and eliminates provision for a separate flocculation facility thereby reduces capital and recurring costs.

Abstract: Methods and apparatus for demulsifying oil in water by dilution and impact, and for separation of the oil and suspended solids by dissolved gas floatation, are described. A produced water treating system is also described. The produced water treating system may include a dissolved gas floatation clarifier system, an oil demulsification system, and a separation system. A demulsification subsystem is also described. The apparatus may include a liquid-liquid fluid mixer and a gas generator.

Abstract: A system, apparatus, and method for treating wastewater having bio-solids therein. The system includes a tank, a wastewater inlet line, an effluent discharge outlet line, and an aeration source. The tank has an upper aeration chamber and a lower clarification chamber separated by a common inclined partition having an opening defined therein. The inclined partition opens into the lower clarification chamber near a bottom of the tank which allows fluid communication between the upper aeration chamber and the lower clarification chamber. The bottom of the tank has a bio-sludge outlet for removal of settled bio-solids. The wastewater inlet line opens into the aeration chamber and an intake end of the effluent discharge outlet line is positioned within the clarification chamber. The aeration source is positioned within the aeration chamber to supply air to the wastewater within the aeration chamber.

Abstract: Detergent formulations are prepared by directly agglomerating a fermentation broth extract, containing a detergent-type enzyme and a nonionic detergent-type surfactant, with a suitable detergent base mixture, without need for prior isolation of the enzyme.

Abstract: A scum removal system for a sewage treatment or clarification tank having a feedwell or skimmer flight includes a scum trough disposed within the settling tank. A floating weir is disposed proximate to the scum trough. A membrane or sheet is partially wrapped or wound about the weir, at least one cable being connected to the membrane for pulling the membrane and concomitantly lowering the weir entrained therewith to permit surface scum to enter the trough from the settling tank. A mechanism for exerting increased tension on the cable to thereby lower the weir below the surface of the liquid in the clarification tank includes a camming lever or arm and an actuator. The lever is connected to the cable, while the actuator is mounted to the feedwell or a skimmer wiper arm so as to engage the camming lever and pivot the actuator lever about an axis.

Abstract: A process is disclosed for preparing a detergent powder containing enzymes where the enzymes are extracted from a fermentation broth with a salt and surfactant mixture and directly agglomerated with detergent paste and dried to form the detergent powder. The process results in a two phase system where the enzyme is extracted into the surfactant rich phase and the second phase is salt rich. The process is especially useful for whole or clarified fermentation broths.

Abstract: An apparatus is provided for cleaning a water treatment tank. The apparatus includes a frame support having post mounted at a central extent of the upper surface of the water treatment tank and extending upwardly therefrom. A horizontally oriented arm has an inboard end coupled to the post. An outboard brush assembly is equipped with a rod coupled to an outboard end of the arm of the frame support and extended downwardly and radially outward therefrom. A vertically oriented brush is coupled to a second end of the rod for cleaning an inner surface of the peripheral lip of the water treatment tank. Also included is a plurality of inboard brush assemblies for cleaning the flanges of the water treatment tank.

Abstract: An apparatus for cleaning algae and debris from the weir, baffle, spillway, and effluent trough surfaces of a sedimentation water treatment tank. A main frame is mounted on the revolving skimmer arm of the tank. A pair of weir cleaning brushes mounted at a lower end of an articulated link arm assembly have bristles facing in inwardly opposed relation engage and clean both sides of the weir and move inward and outward relative to the center of rotation to compensate for out-of-round circular weir surfaces and pivot when their lower ends engage a bracket or obstruction so that they pass thereover and return to a vertical position. A sweeper connected with the weir cleaning brushes spans the space between the baffle and the weir and has elongate flexible strips that dislodge algae and debris and facilitate is passage through the weir and may also clean the surfaces of the baffle and weir.

Abstract: It is necessary in sewage-treatment devices to remove from the waste waters to be cleaned besides the sediment mixtures also impurities which are on the surface of the waste water. This floating matter is according to the invention continuously conveyed into an intermediate container by means of a worm conveyor sweeping over the waste water, from which intermediate container the conveyed matter is discontinuously pumped off.

Abstract: An apparatus for cleaning algae and debris from the inner and outer surfaces of a weir and the top surface and outer side wall of a spillway in a water treatment tank. A main frame is mounted on the revolving skimmer arm of the tank. A pair of brushes pivotally mounted to a lower end of a support arm have bristles facing in inwardly opposed relation to engage each side of the weir for cleaning both side surfaces of the weir. The support arm is connected to the main frame by a universal joint to pivot in a vertical plane and move in and out relative to the center of rotation to compensate for out-of-round weir surfaces. The brushes are spring biased downwardly in a vertical position and pivotally mounted to the support arm to allow pivotal movement when their lower ends engage a bracket or obstruction so that they pass thereover and return to the vertical position. A third brush connected with the pair of brushes engages and cleans the upper surface of the spillway adjacent the weir.

Abstract: A wastewater treatment apparatus comprising a generally circular tank having a wall; a rotatable driven bridge having one end positioned above the center of the tank and an opposite end supported above the tank wall; a sludge moving member supported by the bridge and movable in response to movement of the opposite end of the bridge along the tank wall; and a drive apparatus for moving the opposite end of the bridge along the tank wall. The drive apparatus includes a rail extending along the top of the wall, a frame supporting an end of the bridge, an idler wheel supporting the frame for movement along the top of the wall, a drive wheel rotatably supported on the frame, means for urging the drive wheel into frictional engagement with the surface of the rail, and a drive motor operably connected to the drive wheel for driving the drive wheel along the rail. Preferably, the means for urging the drive wheel is adjustable for controlling the frictional engagement of the drive wheel with the surface of the rail.

Abstract: An underwater clearing device for round sewage treatment basins having an approximately radially extending clearing device formed as a rake blade (8) that is revolvingly driven and sweeps along the bottom (2) of the round sewage treatment basin. The drive of the rake blade (8) being coupled to the rake blade (8) radially on the outside or radially on the inside via a toothed ring (11) provided solely for the revolving movement of the rake blade (8). The rake blade (8) and frame (10) forming a unit arranged under water. A driven transverse conveyor (31) may be provided instead of rake blade.

Abstract: Raw feed water is continuously clarified at a large throughput rate in a single, shallow tank using a flotation process carried out simultaneously in multiple sectors of the tank. Raw water feeds into a rotating trough. A fixed manifold system in the trough dispenses pressurized water containing dissolved air to release microscopic air bubbles. A set of headers each radially extend outwardly from the rotating trough. Each header distributes water and bubbles to a sector of the tank with a net zero velocity. A set of rotating extractors each receive clarified water from the bottom of a preceding sector. A set of scoops skim floated sludge from the water in the tank. The sludge is lifted, as by the rotation of the scoop and/or by a pumped conduit, over the rotating trough to a sludge outlet pipe. In one form the scoop has at least two blades each with an eccentrically located, radially extending compartment that receives, lifts, and then dumps the skimmed sludge as the scoop rotates about its axis.

Abstract: A clarifier comprising a tank, a feedwell, a cover and a raking structure. The cover is rotatably and sealingly engaged with the tank so as to prevent foul air within the tank from escaping into the atmosphere. The feed well and the raking structure are supported by and rotatable with the cover. The clarifier further includes a drive means for rotating the cover.

Abstract: An installation for skimming a vat 1, having a sweeping filter screen 2 whose vertical plane can be rotated so that its bottom edge sweeps the top surface of the contents of the vat 1 so as to remove scum by pushing it towards a spillway 5.

Abstract: An activation plant for the treatment of waste water by the activated sludge method is disclosed wherein the plant has an outer, annular activation tank, a concentric, inner, funnel shaped secondary sedimentation tank, and a rotating aeration bridge rotating about the central axis. The return sludge, excess sludge, and floating sludge chambers, and the associated pumps, are provided in a central shaft that is the central axis for the concentric tanks. The floating sludge chamber is supplied by an annular trough circumscribing the central shaft. Clean water is removed through a conduit in the central shaft. The central shaft, chambers, and aeration bridge are supported by at least three rectangular tubes that are mounted on the wall of the secondary sedimentation tank and extend radially from the conduit for clean water in the central shaft. The rectangular tubes provide a flow space for clean water from the activation plant and are connected to outlet troughs for collecting the clean water.

Abstract: A clarifier tank having a center column is provided with a center-driven bottom rake mechanism for settled sludge removal, a rotating scum rake mechanism comprised of pipes with longitudinal openings for scum removal via the center column, the rake mechanisms rotating in the same or opposite directions at different speeds, and submerged effluent pipes projecting from the sidewall of the tank toward the center of the tank to drain the clarified sewage into an effluent launder exterior of the tank.

Abstract: An apparatus and method for the continuous clarifying of liquids containing suspended solid substances comprises a flotation cell with a liquid head height of less than 1 meter, with a ratio between the liquid head and the cell diameter comprised between 0.25 and 0.05. The cell has a bottom axial inlet for liquid to be clarified, supersaturated with gas, so as to generate an axial ascending current of the liquid to be clarified with radial divarication toward the surface of the liquid head. A framework associated with the cell rotates concentrically with respect thereto and supports a spillway unit for collecting the flotated layer and a scraper unit which affects all the wet surfaces of the cell. A discharge outlet is furthermore provided in the lower part of the cell for the outflow of clarified liquid which falls toward the bottom of the cell.

Abstract: An apparatus for thickening by flotation suspensions contained in a liquid, notably slurries produced during treatment of residual water, formed of a circular basin having a scraping system, the scraping members of which are supported by arms connected to a central device driving them in rotation, or a similar apparatus, and having a flexible cover rotating with the scraping system arms wherein the arms provide the supports for the cover.

Abstract: An apparatus for cleaning algae and debris from a water treatment tank includes a carriage that is mounted for movement while extending over a clean water flow channel of the treatment tank. A motor drives the carriage around the tank while a guide maintains the carriage in the proper position for cleaning. A series of brush assemblies are connected to a frame of the carriage. The brushes of these assemblies are adapted to engage and clean the weir, baffle, spillway and clear water flow channel of the tank as the carriage moves. Additionally, a directional controller automatically controls the direction of operation of the motor and hence the direction of movement of the carriage. The directional controller also includes a sensor adapted to sense any obstructions, such as a service walkway, extending across the movement path of the carriage. Upon sensing an obstruction, the direction of movement of the carriage is reversed.

Abstract: Water clarifying apparatus has a cylindrical tank where particulate contaminants suspended in raw water are separated using flotation techniques. A set of concentric mutually spaced, conical plates are positioned in the flotation tank. The plates rotate about the tank, preferably in unison with a (i) header that distributes equal quantities of raw water to each annular zone in the tank defined by the conical plates and (ii) a scoop for removing the contaminants which form a floated sludge layer. A screw conveyor is located in a discharge pipe of the floated sludge scoop. A infrared sludge detection array in a window in the side wall of the tank senses the sludge-water interface. Air dissolving tubes operating in parallel have common feeds and discharges coupled through three way valves operated to pressurize a closed volume of water with high pressure air in one tube while reloading and discharging the other tube.

Abstract: A peripheral traction unit for a thickener is ground-mounted on a circular support base, normally of concrete, extending circularly at ground level below and exterior of the vertical walls of an above-ground thickener tank. A continuous rail and rack are mounted on a sole plate and integral key embedded and grouted in a support base pocket. A wheel and pinion assembly is provided on a traction frame so that the wheel rolls on the rail and the pinion meshes with the rack. The bottom of a box beam is pin-connected to the traction frame and the top of the box beam is fixedly connected to a rake-driving rotatable truss extending radially or diametrically across and above the tank wall. All erection, adjustment and maintenance of the traction unit is done at ground level rather than at the elevation of the upper edge of the tank wall where heretofore peripheral drive units have been positioned.

Abstract: Support of rake arms in a thickener is by sets of separate support cables and separate torque cables extending from outboard-of-the-center positions of rotating trusses extending radially of the sedimentation tank. The sets of support cables are attached in a vertical plane between spaced positions on a common point on the trusses to spaced radial positions along inner hinged rake arms so that the entire weight of the arms is taken up by the support cables. Torque cables extend from a single point on a truss generally midway of the truss but at a radially offset position from the center line of containing the support cable attachments on the truss or multiple trusses. The torquing or pulling action of the torque cables, also produces no thrust load along the rake arms. This eliminates the need of a heavy large center structure adjacent the rake arm hinges to absorb a rake arm thrust load against the hinges. The hinges are supported by relatively thin posts extending from the rotating trusses.

Abstract: In a sewage treatment system having a series of generally concentric, ring-like treatment tanks, a siphoning head used to withdraw sludge from the bottom of the clarifying tank is propelled slowly and smoothly through its tank by the moving current of sewage in an adjacent tank. Overhead bridge structure supporting the siphoning head in the clarifying tank also overhangs the next adjacent tank and supports a depending baffle which is impinged by the flowing sewage in the adjacent tank. The baffle is positioned closely adjacent the wall between the two tanks such that eddy currents set up in the vicinity of the baffle as the latter is acted upon by the flowing sewage have the effect of entering transfer passages between the two tanks to clean out clogging debris and grease.

Abstract: Apparatus for removing suspended particles from water comprises outer and inner concentrically arranged tanks and a carriage arranged on top of the outer tank for movement around the same. Unclarified water is introduced into the inner tank along with flocculating material for combining with the suspended particles in the water, and the mixture passes from the inner to the outer tank. Gaseous bubbles are introduced into the mixture for attaching to the flocculated suspended particles and floating them to the surface of the water in the outer tank, forming a sludge layer thereon. A scoop device mounted on the carriage removes the sludge for discharge from the apparatus. A plurality of filter beds are arranged near the bottom of the outer tank for removing the remaining precipitated flocs to complete the clarification of the water for discharge, and suction apparatus is arranged above the filter beds for cleaning the same.

Abstract: Waste water treatment apparatus including a vessel for receiving the waste water and having an inlet and an effluent outlet spaced from the inlet. The space between the two defines a flow path for the waste water and a scum outlet is also provided for the vessel. An elongated trough having an elongated opening is disposed horizontally in the vessel at an intended level of waste water therein and extends across the flow path. A movable skimmer blade extending below the intended level of waste water can be drawn along the flow path to capture scum and deliver and deposit the same in the trough through the opening thereof.

Abstract: Apparatus and a method for removing suspended particles from water in a circular tank having a distribution and flocculation chamber immersed in the tank of water and carried circularly around the tank by a carriage. Flocculating material and inlet water are introduced into the body of water from the moving flocculating chamber at the same rate as clarified water is discharged through a filter substantially covering the bottom of the tank. A majority of particles in the water is collected by flocs in the water and floated to the water surface by air bubble action. The floating sludge is removed by a spiral scoop carried by the carriage. The water is then passed through the bottom filter which removes the remaining flocs completing the clarification of the water for discharge. Apparatus is provided for selectively back washing sections of the filter while the remainder of the filter is in operation.

Abstract: The apparatus is suitably disposed within a circular tank and comprises a stationary bridge, a feeding bell, a scraper, driving means, and an optional foam scraping means. The apparatus is characterized in that it has a centrally suspended rotating scraper, mounted from a central vertical shaft and driven by a drive which travels along the rim of the tank, and additionally has at least one rotating drive arm. The drive arm is connected at one end to the drive and at its other end to the feeding bell, which is supported by the shaft of the scraper. The feeding bell is preferably capable of vertical adjustment. The scraper is preferably provided with at least one row of a plurality of vertical stick-like members. A foam scraper is optionally attached to the drive arm. The apparatus additionally contains means for automatically raising or lowering the scraper. depending on the relative rotary momentum between the scraper and the rim drive.

Abstract: A rotary sedimentation apparatus (10), such as a clarifier or thickener, includes a conventional rake arm structure (26, 28, 30) adapted to urge sedimented sludge toward the center of the bottom wall of the apparatus and a centrally mounted drive and lift unit (24) adapted to rotate the rake arm structure. The lifting unit includes an inner cage (84) that is adapted to rotate with the rake arms but to remain at the same elevation when the rake arms are lifted. An improved scum skimming mechanism (12) includes a flat elongate inner blade 40 that is connected by two cables (66 and 68) to the inner cage (84) so that the inner blade remains partially submerged at the liquid level, even though the rake arm structure may be raised. The inner blade is vertically slideably mounted to the upper end of the support frame (50) that extends upwardly from the outer end of a rake arm (30).

Abstract: The disclosure relates to a liquid treatment apparatus which includes a clarifier tank and an integral sludge thickener tank. Liquid enters the clarifier tank through an inlet member disposed generally centrally of the bottom wall of the member and passes upwardly through an eductor member into a mixing zone defined by a reaction cone. Recirculation of liquid and suspended particles below the cone promotes flocculation of those particles. Gravity settling also takes place in the relatively quiescent area outside the cone. The liquid inlet member is of divergent cross-sectional shape for dissipating some of the energy in the liquid and a variable speed rotary impeller is disposed in the inlet and can be adjusted to control liquid circulation according to the flow rate of influent liquid. The apparatus also includes an integral sludge thickener tank to which sludge and liquid are continuously delivered from the clarifier tank.

Abstract: Apparatus for degassing floating solids containing entrapped gas in an open-topped liquid-solid settling chamber wherein floating solids tend to accumulate at the surface of liquid being separated from solids. Liquid containing floating solids is gently agitated in a trough enclosure for degassing of same to form liquid containing degassed solids, and the latter is discharged from the trough disclosure into the liquid-solid settling chamber.

Abstract: A circular decanter includes a stationary hollow column rotatably supporting a bridge which spans the decanter. A trough is integral with the bridge and rotates therewith, whereby sludge drawn by vacuum from the bottom of the decanter is collected in the trough. A sludge evacuation duct is positioned centrally within the hollow column. That portion of the trough which is closest to the column is formed as a siphon having an upstream branch extending downwardly into the sludge collection chamber of the trough and a downstream branch extending downwardly into the sludge evacuation duct. An electric motor for rotating the bridge, trough and siphon is positioned above the column and includes rotating elements attached to the siphon and non-rotating elements. The power supply cables for the electric motor are led upwardly through the column, the sludge evacuation duct and the downstream branch of the siphon and are enclosed within a stationary casing and tube.

Abstract: Apparatus for collection and removal of settled solids from the bottom part of a sedimentation zone, comprising a scraper blade attached to a bridge and drawn reciprocatingly and repetitively in a longitudinal path along the sedimentation zone. Means are provided whereby the scraper blade is drawn toward the end walls of the sedimentation zone for transverse alignment therewith at the approach of the bridge to the end walls, so as to eliminate solids accumulation adjacent thereto.

Abstract: Apparatus for collection and removal of settled solids from the bottom part of a sedimentation zone, comprising a scraper blade attached to a bridge and drawn reciprocatingly and repetitively in a longitudinal path along the sedimentation zone. Means are provided whereby the scraper blade is drawn toward the end walls of the sedimentation zone for transverse alignment therewith at the approach of the bridge to the end walls, so as to eliminate solids accumulation adjacent thereto.

Abstract: A travelling precipitate collector in which a transversely travelling frame is movably provided on a longitudinally travelling frame body, striding over a plurality of sedimentation basins and an elevating frame is vertically movably, interposedly provided in a machine frame which is fixed at the transversely travelling frame body and a chain installed with a plurality of buckets is circulated through the machine frame and the elevating frame, and further, a scraper and a pressure detector are installed on the elevating frame.Owing to the above described structures, the travelling precipitate collector can be prevented defects which are caused from the precipitate clinging to a lower portion of the elevating frame and bending moment acting on the elevating frame can be detected and controlled to thereby protect component members.

Abstract: Sedimentation apparatus which employs an agitator-equipped mixing tank for a feed suspension and a flocculating agent or flocculant, which mixing tank is located within the central feed well of a continuously operating sedimentation tank, and wherein the flocculant-treated feed suspension overflows the top end of the mixing tank, then to continue along a downward path in the surrounding feed well of the tank.

Abstract: Apparatus for clarifying waste water is disclosed in which the waste water being treated is moved through the apparatus with minimum turbulence so that the flotation rate of suspended particles is brought closely to a theoretical value. The apparatus includes a flotation tank unique in that its height is low compared to its area. Inlet pipes for waste water are supported by a carriage which moves around the flotation tank supported on the outer edge of the tank and a runway towards the center thereof. The clarified water is removed by pipes also supported by the carriage and so supported that advantage is taken of the movement of the carriage to effect a longer flotation path for the rising particles.

Abstract: An apparatus for separating solids from liquids by sedimentation includes a covered tank in which a sediment-engaging raking structure is journaled for rotation about a central support pier. The raking structure is driven by a unit which travels about the periphery of the tank outside the enclosure. A gas-tight seal is effected between the tank, the cover and the drive unit by the combination of an annular liquid-holding launder which is fixedly supported to surround the interior of the tank, a rigid U-shaped member which connects the drive unit to the raking structure with its lower portion submerged in the liquid held in the launder, and a continuous baffle-like wall extending from the tank cover downwardly into the space bounded by the submerged portion of the U-shaped member.

Abstract: A sludge settling basin in which a platform is movable over the basin and supports a siphon tube having a first portion extending to adjacent the floor of the basin, a second portion extending over the basin and a third portion extending downwardly into the channel of the side wall of the basin, the material in the channel being removed by a pump with a sufficient rate for the level of liquid in the channel always to be below the level of liquid in the settling basin, so that the sludge is siphoned from the basin into the channel and is removed by the pump.

Abstract: Apparatus for collection and removal of settled solids from the bottom part of an arcuate sedimentation zone, comprising a scraper blade suspended by cable means from a bridge and drawn reciprocatingly and repetitively in an arcuate path around the sedimentation zone. Means are provided for shortening the suspended lengths of the cable means at the approach of the bridge to a radial end wall of the zone so that the scraper blade is drawn toward the wall for radial alignment therewith, thereby eliminating unscraped `dead space` adjacent the end walls.

Abstract: A large sedimentation tank having a traction-driven composite sludge raking mechanism provided with lift capability, and comprising a rotary traction-driven drive arm of girder-like construction exposed above the liquid level, and draft-connected to an inner load yielding self-liftable rake arm operating in the central sludge accumulation zone in the tank, and also connected to an outer complementary rake structure operating in an outer annular zone to move sludge therefrom into the central accumulation zone.

Abstract: A sludge removal system for use in the removal of settled sludge collected on the bottom surface of a circular clarifier. The system includes a plurality of self-supporting sludge receiving conduits of various lengths extending radially outward from the center of the tank in a common horizontal plane. Each conduit has a sludge pick-up port associated with the outer end thereof. Vertical riser tubes extend upward from the inner ends of the conduits into a sightwell assembly. At the upper end of each riser tube is a flow control valve arrangement to regulate the amount of sludge flow through each conduit. The valve indicates a pipe within a pipe, both pipes having slotted openings cut therefrom, to provide a variable flow orifice the size of which may be controlled by rotating the inner pipe about the stationary outer pipe. The upper edges of the slotted openings extend above the static liquid level in the clarifier.

Abstract: Cartridge heaters are most frequently used for heating metal parts by insertion into bores in such parts. Such heaters are manufactured in various diameters to closely fit within complementary bores to provide heat according to required specifications. My invention makes it possible to use a heater of known sheath diameter in bores of larger diameter, by use of metal sleeve means which have an inside diameter to closely receive the heater and an outside diameter to closely fit within the bore.