SYSTEM FOR CONTINUOUSLY TREATING SOLID WASTE AND ASSOCIATED PROCESS THEREOF

Abstract

The present invention relates to a system for continuously treating solid waste and an associated process based on steam injection at a temperature greater than 100° C. and at a pressure greater than the atmospheric pressure, which allow a high productivity to be achieved, require a smaller volume of the pressure vessel needed carry out the solid waste treatment, and reduce the amount of steam needed to carry out said treatment.

Claims

1. A system for continuously treating solid waste, characterised in that it comprises: a pumping device (1) configured to continuously pump and compact a solid waste flow, wherein the pumping device (1) comprises an inlet (2) configured to carry out the suction of the solid waste flow at a first pressure comprised in the range [0; 1] barg, in other words, at a relative pressure with respect to the atmospheric pressure, and an outlet (3) configured to pump the solid waste flow at a second pressure that is greater than the first pressure; a pressurised tubular vessel (4) configured to maintain the pressure of the solid waste flow at the second pressure; at least one steam injection device (5) for injecting steam in the solid waste, configured to heat and break up the solid waste inside the pressurised tubular vessel (4); an extraction device (6) configured for extracting the treated solid waste from the pressurised tubular vessel (4) and for reducing the pressure of the flow of the treated solid waste in a controlled manner from the first pressure to the second pressure.

2. The system for continuously treating solid waste according to claim 1, characterised in that it further comprises a flash chamber (7) arranged after the extraction device (6), wherein the flash chamber (7) comprises an assembly of breakers configured for crumbling the treated solid waste.

3. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it further comprises a hopper (8) configured to receive the solid waste prior to the passage thereof through the pumping device (1).

4. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it further comprises a preheating and degassing device (9) configured to preheat the solid waste flow and eliminate the trapped air between the particles of said solid waste prior to the passage thereof through the pumping device (1).

5. The system for continuously treating solid waste according to claims 2 and 4, characterised in that the preheating and degassing device (9) comprises a device for the inlet of water and/or condensates (11) recovered from the process and/or a device for the inlet (14) of flash steam into the preheating and degassing device configured for adjusting the moisture of the solid waste prior to the passage thereof through the pumping device.

6. The system for continuously treating solid waste according to claim 5, characterised in that it comprises means for regulating the water inlet and/or condensates by means of the device for the inlet of water and/or condensates and/or the device for the inlet of flash steam into the preheating and degassing device.

7. The system for continuously treating solid waste according to any of claims 4 to 6, characterised in that it further comprises a condensation device (10) to which the waste steam that has not condensed in the preheating and degassing device (9) is sent.

8. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it further comprises one or several post-treatment devices (12) configured to carry out the drying and/or separation by particle size and/or densimetric separation of treated solid waste.

9. The system for continuously treating solid waste according to any of the preceding claims, characterised in that the pumping device (1) is a positive displacement device.

10. The system for continuously treating solid waste according to any of the preceding claims, characterised in that the pressurised tubular vessel (4) has a circular cross section.

11. The system for continuously treating solid waste according to claim 1, characterised in that the at least one steam injection device (5) for injecting steam in the solid waste is inserted along the pressurised tubular vessel (4).

12. The system for continuously treating solid waste according to any of the preceding claims, characterised in that the extraction device (6) is a positive displacement device, configured for extracting the treated solid waste from the pressurised tubular vessel (4) and for reducing the pressure of the flow of the treated solid waste in a controlled manner, preferably with each positive displacement, from the first pressure to the second pressure.

13. The system for continuously treating solid waste according to any of the preceding claims, characterised in that the preheating and degassing device (9) is a solid-steam counterflow heat exchanger.

14. The system for continuously treating solid waste according to any of the preceding claims, characterised in that the outlet (3) of the pumping device (1) is configured for pumping the solid waste flow at the second pressure, greater than the first pressure, comprised in the range [1; 20] barg.

15. The system for continuously treating solid waste according to claim 14, characterised in that at the inlet (2) of the pumping device (1) the suction of the solid waste flow is carried out at a first pressure comprised in the range [0; 0.5] barg, and at the outlet (3) the pumping of the solid waste flow is carried out at the second pressure, comprised in the range [2; 10] barg.

16. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it comprises control means configured for controlling the treatment temperature of the solid waste, regulating the steam injection by means of the at least one steam injection device (5) for injecting steam in the solid waste.

17. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it comprises control means configured for controlling the pressure of the treated solid waste flow downstream from the extraction device (6) regulating the extraction speed of said treated solid waste.

18. The system for continuously treating solid waste according to any of the preceding claims, characterised in that it comprises control means configured for controlling the flow of the solid waste that is introduced in the pressurised tubular vessel (4) regulating the pumping speed of said solid waste by means of the pumping device (1).

19. A process for continuously treating solid waste, characterised in that it comprises the following stages: a pumping stage configured for carrying out the pumping of a solid waste flow in a continuous and compact way, from a first pressure comprised in the range [0; 1] barg, in other words, at a relative pressure with respect to the atmospheric pressure, to a second pressure that is greater than the first pressure; a stage of maintaining the pressure of the solid waste flow in a confined manner at the second pressure; a stage of injecting steam in the solid waste, wherein the heating and breakup of the solid waste is carried out in a confined way; and a stage of extracting the treated solid waste, wherein the reduction of the pressure of the flow of the treated solid waste is carried out in a controlled manner from the second pressure to the first pressure.

20. The process for continuously treating solid waste according to claim 16, characterised in that the stage injecting steam in the solid waste is carried out at speeds greater than 20 m/s.

21. The process for continuously treating solid waste according to any of the claim 19 or 20, characterised in that the stage of injecting steam in the solid waste is carried out in a uniformly distributed manner throughout the entire perimeter of the solid waste and/or in several sections of the same.

22. The process for continuously treating solid waste according to any of the claims 19 to 21, characterised in that the stage of injecting steam in the solid waste is a stage of injecting steam at a temperature greater than 100° C.

23. The process for continuously treating solid waste according to any of claims 19 to 22, characterised in that it further comprises a flash stage after the extraction stage wherein the crumbling of the treated solid waste is carried out.

24. The process for continuously treating solid waste according to any of the claims 19 to 21, characterised in that it further comprises a stage of preheating and degassing the solid waste flow prior to the pumping stage.

25. The process for continuously treating solid waste according to claim 24, characterised in that the stage of preheating and degassing the solid waste flow comprises a sub-stage of the injection of water and/or condensates recovered from the process.

26. The process for continuously treating solid waste according to any of the claims 19 to 25, characterised in that it further comprises one or several post-treatment stages wherein the drying and/or separation by particle size and/or densimetric separation of treated solid waste is carried out.

27. The process for continuously treating solid waste according to any of the claims 19 to 26, characterised in that the second pressure of the pumping stage is comprised in the range [1; 20] barg.

28. The process for continuously treating solid waste according to claim 27, characterised in that the first pressure of the pumping stage is comprised in the range [0; 0.5] barg and the second pressure is comprised in the range [2; 10] barg.

29. The process for continuously treating solid waste according to any of the claims 19 to 28, characterised in that it comprises a stage of controlling the temperature of the solid waste after the stage of injecting steam in the solid waste.

30. The process for continuously treating solid waste according to any of the claims 19 to 29, characterised in that it comprises a stage of controlling the solid waste flow before the stage of injecting steam in the solid waste.

31. The process for continuously treating solid waste according to any of the claims 19 to 30, characterised in that it comprises a stage of controlling the treatment pressure of the solid waste before the extraction of said treated waste.

Description

DESCRIPTION OF THE DRAWINGS

[0056] As a complement to the description provided herein and for the purpose of helping to make the characteristics of the invention more readily understandable, in accordance with a preferred practical embodiment thereof, said description is accompanied by a set of drawings constituting an integral part of the same, which by way of illustration and not limitation represent the following:

[0057] FIG. 1 shows a diagram of the system for continuously treating solid waste and the associated process thereof of the present invention.

PREFERRED EMBODIMENT OF THE INVENTION

[0058] The system and process for continuously treating solid waste of the present invention is described in a detailed way below.

[0059] The system for continuously treating solid waste comprises: [0060] a pumping device (1), preferably a positive displacement pump, configured to continuously pump and compact a solid waste flow, wherein the pumping device (1) comprises an inlet (2) configured to carry out the suction of the solid waste flow at a first pressure comprised in the range [0; 1] barg, in other words, at a relative pressure with respect to the atmospheric pressure, preferably comprised in the range of [0; 0.5] barg, and an outlet (3) configured to pump the solid waste flow at a second pressure that is greater than the first pressure comprised in the range [1; 20] barg, preferably comprised in the range [2; 10] barg; [0061] a pressurised tubular vessel (4), preferably with a circular cross section, configured to maintain the pressure of the solid waste flow at the second pressure; [0062] at least one steam injection device (5) for injecting steam in the solid waste, configured to heat and break up of the solid waste inside the pressurised tubular vessel (4); wherein the at least one steam injection device (5) is inserted along the pressurised tubular vessel (4); and
an extraction device (6), preferably a positive displacement device, configured for extracting the treated solid waste from the pressurised tubular vessel (4) and for reducing the pressure of the flow of the treated solid waste in a controlled manner, preferably with each positive displacement, from the first pressure to the second pressure. There is a residence time of the treated solid waste in the pressurised tubular vessel (4) that depends on the volume of the section of the tubular vessel comprised between the steam injection device (5) and the extraction device (6), as well as on the waste flow pumped by the pumping device (1).

[0063] The system further comprises a flash chamber (7) arranged after the extraction device (6), wherein the flash chamber (7) comprises an assembly of breakers configured for crumbling the treated solid waste.

[0064] The system further comprises a hopper (8) configured to receive the solid waste prior to the passage thereof through the pumping device (1).

[0065] The system comprises a preheating and degassing device (9) configured to preheat the solid waste flow and eliminate air trapped between the particles of said solid waste prior to the passage thereof through the pumping device (1), wherein the preheating and degassing device (9) is a solid-steam counterflow heat exchanger.

[0066] The system comprises a condensation device (10) to which the waste steam that has not condensed in the preheating and degassing device (9) is sent.

[0067] The preheating and degassing device (9) further comprises nozzles (11) for the injection of water and/or condensates recovered from the process for moistening the solid waste and improving the subsequent treatment in the line thereof by means of the steam injection devices.

[0068] The system further comprises one or several post-treatment devices (12) which, based on the quality of the final material to be obtained, could be a dryer, a sieve and a densimetric separator, configured to carry out the drying and/or separation by particle size and/or densimetric separation of the treated solid waste.

[0069] The process for continuously treating solid waste comprises the following stages: [0070] a pumping stage wherein the pumping of a solid waste flow is carried out in a continuous and compact way, from a first pressure comprised in the range [0; 1] barg, in other words, at a relative pressure with respect to the atmospheric pressure, preferably comprised in the range [0; 0.5] barg, to a second pressure that is greater than the first pressure, comprised in the range [1; 20] barg, preferably comprised in the range [2; 10] barg; [0071] a stage of maintaining the pressure of the solid waste flow in a confined manner at the second pressure; [0072] a stage of injecting steam in the solid waste, preferably at speeds over 20 m/s, wherein the heating and breakup of the solid waste is carried out in a confined way; and [0073] an extraction stage of the treated solid waste wherein the reduction of the pressure of the flow of the treated solid waste is carried out in a controlled manner from the second pressure to the first pressure. Preferably, the steam injection stage is carried out in a uniformly distributed fashion on the entire perimeter of the solid waste and/or on several sections of the same.

[0074] Said stage of injecting steam in the solid waste is a steam injection stage at a temperature above 100° C.

[0075] Due to the special configuration thereof, the system and process for continuously treating solid waste allow a high productivity to be achieved, require a smaller volume of the pressure vessel in order to carry out the solid waste treatment and reduce the steam consumption needed to carry out said treatment.

[0076] The process further comprises a flash stage after the extraction stage wherein the crumbling of the treated solid waste is carried out.

[0077] The process further comprises a stage of preheating and degassing the solid waste flow prior to the pumping stage. Based on the type of solid waste, said stage can include a sub-stage of injection of water or condensates recovered from the process in order to increase the moisture and improve the subsequent treatment in the line of the solid waste in the steam injection stage.

[0078] The process further comprises a stage of condensing the excess waste steam after the preheating and degassing stage.

[0079] The process further comprises one or several post-treatment stages, wherein the drying and/or separation by particle size and/or densimetric separation of the treated solid waste is carried out.

EXAMPLE

[0080] Several tests of continuously treating solid waste were carried out. In several of them the organic fraction of municipal solid waste (OFMSW) with a particle size of less than 80 mm mesh size was used as waste.

[0081] In the previous stage of preheating, degassing and moisture adjustment, the solid waste is conditioned by injecting steam and condensates recovered from the process to bring it to a temperature of 80° C., eliminating the gasses trapped between the particles thereof and adjusting the moisture thereof from initial approximately 48% up to the complete saturation thereof corresponding to 100% of moisture.

[0082] A solid waste flow of 15 t/h is adjusted at the beginning of the process which, after passing through the preheater and degasser, is sucked by the positive displacement pump at a pressure of approximately 0.2 barg and pumped at a second selected working pressure of 5 barg.

[0083] After entering into the pressurised tubular vessel, the injection of the steam from the heating vessel takes place, which breaks up and heats the solid waste to the temperature of the saturated steam at the selected working pressure. To complete the treatment, said working temperature is maintained during a residence time of the solid waste in the pressurised tubular vessel for 10 minutes.

[0084] Lastly, the treated solid waste is depressurised in a controlled way with the resulting recovery of the steam (13) produced by the flash of the material.