FR2486060A1 - Installation to purify and cool domestic effluent etc. - uses cooling vessel with upflow injection to avoid fouling heat transfer surface - Google Patents

Abstract

Appts. for the purificn. and cooling of domestic effluent etc. by removal of grease, detergent scum etc. and by recuperation of heat for re-use, is described. The recuperative heat exchanger comprises cooling surfaces inside a vessel into which the effluent is injected upwards from the base. The upflow of effluent prevents the settlement of impurities as cooling proceeds. Pref. flow through the heat exchanger is controlled to produce laminar flow which entrains the impurities and carries them to an overflow discharge. This discharged effluent is pref. passed through a grease trap comprising filtration and decantation in series. Appts. is for purifying and cooling hot, domestic effluent etc., before discharging it to drainage systems. Heat is recovered for domestic use, e.g. hot water systems as the effluent is cooled. The upflow through the heat exchanger vessel prevents fouling of the heat transfer surfaces. The system is equipped with in place cleaning.

Description

 This ention concerns @r ech @@ cold geur, working or not in connection with a filtering and separation device and intended to allow the thermal recovery and the separation of greases, from a circuit of waste water coming for example of a housing unit.

 The cold heat exchanger devices operating in laden water have in common a drawback which considerably limits their use: the exchange surfaces very quickly become covered with greasy dirt which thermally insulates them.

 Thus it becomes practically impossible to recover the thermal energy included in such water, in particular that leads to rejecting down the drain all the thermal load of water passing through a housing unit. On the other hand, in the case of a housing unit not connected to a sewer network, the rejection of hot water regularly leaches (at each emptying of a washing machine) the grease traps. The fat thus released is redeposited in the spreading fields or on the bacterial trays and disrupts its functioning.

 Tests have been carried out on treatment devices and the installations always include a waste water storage tank, insulated tank, in which a passive or active exchanger takes the thermal load to transfer it to another tank also insulated and storing clean hot water. These installations, despite the presence of detergents in the treated water, behave as described above.

 The object of the present invention is to overcome this denial and allow thermal recovery of the charged water. It is also to reject water released from its fats and detergent deposits.

 These goals are achieved by arranging the various interested bodies, for example, in the following manner.

 The loaded water, coming from the various stations of use of a housing unit, is gathered in a common recovery point and undergo a first filtering intended to stop accidental foreign bodies. This recovery point includes a direct evacuation towards the rejection in the event of clogging of the filter and a signaling of this clogging. From this point, by gravity, by recovery pump or by any other means, the water is directed to a storage tank.

Co rese @@ storage sir can be fitted to limit its level of soiling by providing various devices such as an anti-stick interior coating (epoxy, PTFE, enamel or other) and / or an upper inlet comprising an arm rotary sprinkler spraying edmiee water on the walls
From the storage tank, the water is directed to a so-called thermal transfer tank through a valve or a pump and a valve which are intended to cause a distribution of water only during preferential moments.

In the heat exchange tank, the water supply is provided at the bottom through a jet breaker and the outlet is made by overflow at the top. Some distance below the finish level by said upper part is placed the cold exchanger. This exchanger can be passive by heat pipes by circulation of heat transfer fluid, by effect
Peltier or in general by any system capable of performing thermal transfer.

During the cooling phase, the circulatory circulatory is established by causing a gradual descent of the cold layers from the exchanger and, as the cold exchanger is at the top, all the water in the reservoir is gradually cooled heat exchange - At the end of the cooling phase, grease and dirt are sound; accumulated towards the upper part or they close a continuous layer. The cooling limit temperature can be adjusted so as to obtain or not a solidification of the greases.
The next phase is that of lukewarm or hot water, which, arriving from the bottom and the jet breaker causes the heat exchange tank to overflow and the evacuation of the layer of dirt, taken in the laminar flow of overflow. By the way, these waters clean the exchanger since they are hot. If necessary, an injector placed before the entry of said tank can introduce a few drops of detergent to facilitate cleaning.

 A natural and particular advantage to this device is that a continuous circulation of a few minutes may be sufficient for periodic cleaning of the heat exchange tank.

 The cold waters thus treated are directed to a final filtering combined with a settling tank intended to retain the greases.

 Other particular advantages of this device will be understood by following the description below @ us referring to the diagram (1) representing a complex version of a thermal recycler of domestic water.

 The collection piping (1) is terminated at its bottom by a filter (21) followed by a lift pump (2) asserw life to a pressure switch 3) noting the presence of water. The octopus (2) flows into the heat-insulated storage tank (4) and in this tank a spray arm (5) cleans the walls of the tank (4) at each water inlet.

 At the lower part of the tank (4) a pump (6) followed by a valve (7) can discharge periodically into a strip in Je. pink see heat exchange (8) a pressure switch (9) is also prevn at the bottom of the buffer tank (4) In the tank i 8) we see the jet breaker (10), the shape of the upper edge (11 ) intended to promote a laminar overflow and the cold exchanger (12). An injector (13) is placed before the tank (8) and a thermostat (14) at the top of the same.

 After the heat exchange tank (8) overflows, the water is directed to an assembly comprising a filter (22) and a decanter (23) from which they are then discharged The filters (21 and 22) as well as the decanter ( 23) are grouped in the same organ from which the filters can be removed for cleaning or changing and the cleaning of which is easy.

 The cold exchanger (12) is the evaporator of a refrigeration unit (15) operating as a "heat pump" and, the condenser (16) of which is embedded in a tank (17) for heat recovery, The latter is a ordinary storage water heater, for example electric, therefore comprising a heating resistor (18) and a thermostat (19) and provided with annexed piping intended for the introduction of the condenser.

 This set works as described above.

Consider the cycle when the cooling of the tank (8) is finished. The thermostat (14) then stops the group (15) and starts the pump (6). This start-up is also subject to the presence of water in the tank (4) observed by the pressure switch (9). During the operation of the pump (6) a pulse may other sent to the injector (13). back water
blowing into the tank (8) by the jet breaker (10) causes the
@ o @ dement by the edge (11) causing dirt.

The arrival of warmer waters soon causes the thermostat (14) to cool down, which stops the pump (6) and restarts the unit (15). The latter is also controlled by the thermostat (19) and can only operate if it is not at its maximum
The diagram (2) represents the circuit of elettic connection and one finds there the elements of diagram 1 with the same references - in addition, a relsiz (200 of tariff "ereuses hours"
EDF "is planned.

 Note the ease of cleaning the cold exchanger, which can be obtained by deliberate circulation of water and detergents.

 Eien heard the invention is not limited to the described case of an associated electric water heater and can be extended to the case of a gas storage water heater. On the other hand, the invention is not more limited to the case of the housing unit and the operating principle can be extended to all ca @ thermal recovery, interesting liquids laden with dirt being deposited at low temperature and density lower than that of the liquid.

Claims (6)

t'Ni) 1CATIONffi  1) wastewater treatment assembly characterized in that it comprises a heat exchanger in which the direction of circulation of the water to be cooled is effected from bottom to top so as, inter alia, to push up the dirt deposited during the cooling phases.  2) wastewater treatment assembly characterized in that it comprises a heat exchanger operating as (1) above and comprising a cyclic operation with the introduction of less cold water and cooling phases and as during the phases introduction, made by the lower part, the outlet of the cooled water and laden with frozen grease takes place in a laminar regime, by overflow, and entraining the said frozen water.  3) wastewater treatment assembly characterized in that it comprises a heat exchanger operating as in 1 and 2 above and comprising an injection device capable of injecting a detergent product intended to promote the floating of fatty soils .  4) wastewater treatment unit characterized by a device for filtering and settling grease receiving water that has been previously cooled. which facilitates the trapping of grease and liquid soap sludge.  5) wastewater treatment unit characterized by a device for filtering and settling grease receiving water previously cooled and constituting a grouping at one point of the discharges of domestic water.  6) wastewater treatment assembly characterized by a device for filtering and settling grease receiving water previously cooled and rejecting degreased water because it has cooled and therefore improves the operation of the downstream purifiers.