DE2019731B2 - Process for treating sewage sludge to improve its drainage properties and device for carrying out the process - Google Patents

Description

2. Device for carrying out the process quickly encrusts, thereby reducing the passage of heat according to claim 1, characterized in that as is reduced and the pressure loss in the double pipe per Pressure stage a heat exchanger divided into two rooms is increased. It can even be bought for Pressure vessel is provided, the lower of which completely clogs the pipes of the double-pipe space (11) come as an evaporator and its upper heat exchanger. The purification of such Space (12) is designed as a mixing condenser. Pipes is very expensive.

3. Apparatus according to claim 2, characterized in that the invention is based on the object indicates that between the rooms (11, 12) to modify known methods so that the structural a partition (10) and in the partition (10) expense for the recovery devices a connecting pipe (13) are provided. the heat from the conditioned sludge

4. Apparatus according to claim 2 or 3, characterized will wrestle and in particular high pressure characterized in that in the space (12) of the pressure 35 losses in the heat exchanger avoided as well as container devices for generating a heat-transferring surfaces caused by the oversized mud surface such. B. encrust cascade water sludge, discontinued werbleche (14a, 14b), nozzles or rotating plates, the.

are provided. This object is achieved according to the invention

40 solved that the raw sludge via at least one intermediate stage from the initial state to the im Reactor for conditioning brought the prevailing pressure and the conditioned sewage sludge

from the reactor pressure via the same intermediate

45 stages is relaxed and that the raw sludge in these intermediate stages through direct contact with the vapors of the conditioned sewage sludge released during the relaxation in each case approximately heated to the corresponding saturation temperature. The invention relates to a method for applying 50 is.

treatment of sewage sludge for improvement through the direct heat exchange between the

its dewatering properties, in which in the vapor and raw sludge not only the continuous flow of the sewage sludge is subjected to the heat transfer thermal conditioning required in the known process and the surfaces are avoided, but there is also a very good heat transfer with the heat of the outflowing conditioned 55 guaranteed. The Ent-sewage sludge is largely transferred to the incoming tension or pressure increase in intermediate stages of raw sludge. Furthermore, it relates to a device for carrying out this raw sludge from the heat exchanger to achieve a higher outlet temperature than in the case of heat exchangers e.g. in the primary sludge, secondary and vice versa for the pressure increase) without the intermediate sludge, digested sludge and similar sludge, intermediate stages is possible. Also, the colloids contained in the flake structure are destroyed under increased pressure and the conditioned sludge by the relaxation of increased temperature, which is more gentle over intermediate stages than with a slight separation of the sludge solids from the remaining relaxation in a single pressure stage,
borrowed water through z. B. settling, filtering or the device for performing this centrifugation becomes possible. For an economical process, according to the invention, a pressure vessel divided into two spaces is provided for each pressure stage in the operating mode of this process,

3 4

its lower room as an evaporator and its table shown in the drawing and is in the foloberer Space is designed as a mixing condenser. described in more detail. The drawing shows the

These pressure vessels thus replace the parts of a device that are essential for the invention in the case of conventional parts Systems required long double pipes with three pressure stages.

cables. 5 In reactor 1, the colloids of sewage sludge are considerably reduced. Heat exchange surfaces are no longer available at increased pressure and temperature, so that incrustations are no longer a problem. As a pressure vessel, three direct heat can emerge. Those previously provided in heat exchanger 2a, 2b, 2c . In these the unavoidable high pressure losses, raw sludge, which is largely avoided with the help of pumps 3 a, 3 b, 3 c. Operation and maintenance io 3d in pressure stages in the direct heat exchanger 2 c, costs willow reduced. 2b, 2a and the reactor 1 is pumped, staged

To make a mixture of the raw sludge with the wise warmed. Expansion valves 4a, 4b, 4c, 4d to avoid conditioned sludge, at the same time ensure the gradual pressure reduction of the condenser to direct the vapors from the evaporator into the mixed sludge from the reactor pressure to the condenser, is between the lower 15 withdrawal pressure of the device. A partition wall via the gas outlet and the upper space and a connecting pipe is provided in the valves Sa, 5b, 5c, 5d, exhaust gas from the reactor 1 partition wall. The and the direct heat exchangers 2 a, 2 b, 2 c from the arrangement of the connecting pipe left in the partition. The exhaust gas consists of carbon dioxide-rich, has the advantage that pressure-bearing walls, non-condensable gas, which comes from organic sludge components through welds or the like for the connecting pipe, mixed with water. steam.

According to a further embodiment of the invention, pipes 6a, 6b, 6c, 6d are used for the supply of the raw sludge in the upper space of the pressure vessel to the direct heating system to generate a large sludge upper exchanger 2c, 2b, 2a and the reactor 1 such as B. cascade plates, nozzles or ro- 25 the pipe 6e is the supply of foreign animal plates, provided to allow an intimate mixture of steam in the reactor 1. Through pipes la, the raw sludge with the vapors. Ib, lc, Id is the conditioned sludge from the

It is true that the German patent specification Reactor 1 describes a continuous process via the direct heat exchangers 2a, 2b, 1 241 381, and 2c is derived from the device. The exhaust gas from where the sludge - after mixing 3 ° the reactor 1 and the direct heat exchangers 2 a, with an oil - under gradual pressure and temperature 2b, Ic is through pipes 8a, Sb, 8c, 8d over temperature increase of a heat treatment is pulled under the gas discharge valves 5a, 5b, 5c, 5d of a pipeline 9. The heat is supplied at the highest level, through which the exhaust gas allows the device to pass through the supply of live steam from a stage. The partition 10 divides the direct heat from boiler, in each of the further stages by exchangers 2a, 2b, 2c in the lower room 11, leading to the next higher level from which it is used as evaporation, and the upper room 12 , Sludge evolved steam. It is designed as a mixing capacitor. However, by a method in which the sludge the connecting pipe 13, the spaces 11 and 12 are dewatered by evaporation. The heat in connection with each other, whereby the transition in room 11 in the individual stages can therefore only 4 ° released vapors are fed to room 12 directly, ie with the interposition of warming. For the fine distribution of the raw sludge in the transferring surfaces, there is a direct space 12 in which the cascade plates 14a, 14 * are connected to heat exchange, which is brought about with a condensate intake. The raw sludge can also be connected with the aid of the purpose of the process, namely by nozzles, rotating plates or otherwise sprayed and dewatering by evaporation to be carried out. The number of pressure levels for the heat transfer would run counter to. In the exemplary embodiment, this known interchange is three, so the person skilled in the art could not drive a suggestion. fewer pressure levels are used. Preferential

Even the warming of raw sludge by wise three to six pressure levels for the direct contact with vapors is known per se 50 heat exchange is used.

(see Swiss patent specification 458 226). The new device works as follows: The

In contrast to the invention, the well-known raw sludge is not driven continuously by the pump 3a, but rather a batch pipeline 6a into the room 12 of the direct heat pass. Here, after the completion of an under exchanger 2 c, where it is distributed βϊητ 55 the cascade plates 14a, 14b when it hits an elevated temperature, and the charge in the reactor and after extensive pressure through the heat of condensation from the expansion of space 11, the vapors heated from the reactor in a rising vapor. The piped into this pressure storage tank, in which the next stage heated raw sludge and the vapor condensate batch for preheating is already located. From this pressure sat the pump 3b through the pipeline 6b , however, the skilled ^{person cannot convey any indication 6} ° into the next direct heat exchanger 2b , on how to carry out a direct heat exchange in this and in the direct heat exchanger 2a again in a continuous process the process described. Finally, there is a particular difficulty in overcoming the preheated raw sludge by the pump 3d, bridging the pressure difference with continuous, brought to the pressure in the reactor 1 and operating there, as well as the requirement for a 65. By mixing the reactor as complete a heat recovery as possible with external steam that comes through the pipe, line 6 e is fed, the required

One embodiment of the invention is achieved schema reactor temperature. After a necessary

Residence time of the raw sludge supplied above, the now conditioned sludge leaves the reactor 1 below through the pipeline la and is expanded in the expansion valve 4 a to the pressure prevailing in the direct heat exchanger 2 σ. The conditioned sludge cools down with the formation of steam. In room 11 of the direct heat exchanger, conditioned sludge and steam are separated from one another, the vapors rising into room 12 and mixing there with less warm raw sludge, while the condiüonierte sludge flows down through the pipe 7 b from the direct heat exchanger la and again in the expansion valve Ab is relaxed. The process described is repeated in the direct heat exchangers 2b and Ic , and a largely cooled, conditioned sludge then leaves the device through the pipeline Id.

Using the respective gas discharge valve 5a or 5b or 5c and 5d the pressure in the reactor and the individual Direktwärmeaustauschern 2a, 2b, 2c set high pressure in the reactor 1 results in low vapor loss by the exhaust gas, but also requires a correspondingly higher pump performance . For the pressure in the respective direct heat exchangers 2 a, 2 b, 2 c , under given conditions, the highest possible temperature of the raw sludge emerging from the space 12 is the decisive criterion.

Ideally, i. H. inter alia in the complete absence of inert exhaust gas and in the case of perfect Heat exchange, make z. B. enter the following temperatures:

description Direct
Ic värmeaust
26th auscher
la reactor
1 Raw sludge
Entry
temperature
⁰ C 55
100 100
138 138
171 171 Exit
temperature
⁰ C 138
100 171
138 200
171 Conditioned
mud
Entry
temperature 200 Exit
temperature
⁰ C

In fact, this is the exit temperature of the raw sludge from any direct heat exchanger for the reasons mentioned above, slightly lower than the outlet temperature of the conditional

^a 5 nated sludge from the same direct heat exchanger.

If, on the other hand, the heat exchange were carried out in a single stage, this would only result result in an outlet temperature of 138 ° C, d. H.,

the raw sludge would be at a much lower temperature than with the three-stage process get into the reactor.

1 sheet of drawings

Claims (1)

1 2 like that for the heating of the sewage sludge patent claims: to keep the necessary amount of heat as low as possible. In a known method that meets these requirements 1. Process for the treatment of wastewater demise is fulfilled, the wastewater sludge is under sludge to improve its drainage 5 increased pressure in the closed reactor 30 to properties, in which in continuous operation 45 minutes at a temperature of about 17C to The sewage sludge is kept at a thermal temperature of 200 ° C, after which the sludge solids Is subjected to conditioning and can be separated very easily from the remaining water, the heat of the outflowing conditioned waste within the framework of an economical operating mode water sludge largely on the inflowing io the process is carried out continuously and the Raw sludge is transferred, thereby characterizing conditioned sludge in countercurrent to the raw sludge, that the raw sludge over sludge through a double tube heat exchanger at least one intermediate stage guided from the output, the conditioned sludge being removed on the in the reactor for the conditioning cools and the raw sludge is heated (prospectus of pressure and the 15 company Technfina S. A., 1200 Geneva / Switzerland, print shop conditioned Sewage sludge with the symbol SCH 68/2000, pp. 2, 5 and 6, with reference to actuator pressure via the same intermediate stages, corresponds to British patent specification 909 872). is tensioned and that the raw sludge in this Intermediate stages through direct contact with the tube heat exchanger below that in the reactor the relaxation released vapors of the high system pressure of around 15 to 25 atmospheres. conditioned sewage sludge in each case. The fact that approximately to the corresponding saturation temperature, especially at temperatures of the sewage sludge is heated. of over 100 ° C the heat transferring surfaces