MXPA96002643A

MXPA96002643A - Method to produce a combusti product

Info

Publication number: MXPA96002643A
Application number: MXPA/A/1996/002643A
Authority: MX
Inventors: A Lavelle William Iv
Original assignee: A Lavelle William Iv
Filing date: 1996-07-05
Publication date: 1998-01-01

Abstract

The present invention relates to a method for the production of a fuel energy product from biological sediments characterized in that it comprises: a) mixing a renewable bulking agent with the sediments, b) aerobically composing the mixture of the first step a) under conditions effective to obtain a temperature of about 77 ° C (170 ° F) to about 79 ° C (175 ° F), c) maintaining the temperature of the mixture at about 77 ° C (170 ° F) to about 79 ° C ( 175§F) for a period of time sufficient to substantially reduce the pathogenic microorganisms and produce a mixture of composted products having a moisture content up to 45%, and d) separate the bulking agent from the mixture of composted sediments to produce a residual product treated fuel, which will have a calorific value of approximately 2,111 cal / g (3,800 Btu / lb) to 5,773 cal / g (10,300 Btu / l)

Description

"METHOD TO PRODUCE A COMBUSTIBLE PRODUCT" Description of the invention_ This invention is related to a method to produce combustible products from sediments or biological waste and the products produced by them.

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Biological waste sediments are a problem of global growth. In the United States, the; Sewage sludge exceeds 20,000 tons / day and costs for disposition or disposal have increased rapidly due to prohibitions on throwing into the oceans and having a decreasing capacity in landfill areas. The unlimited resources of blackwater sediments can be processed for use as soil conditioners or fertilizers. In the United States, the regulations of the Environmental Protection Agency (EPA) must be complied with regarding the concentrations of residual pathogens before processing the sediments, and only a small fraction of the sediments generated are converted to this final product. Composting (production or composting) has been used as a method to dispose of blackwater sediments. Methods for producing a compostable mixture of sewage sludge are described in U.S. Patent No. 4,659,472. A material such as sawdust is mixed with the wet sediments of the sewage in the presence of air. The mixture is administered with a polyelectrolyte solution and then pressed with a solids content of 30% solids by weight. The resulting compostable mixture can be subjected to a composting process having a volume of 15-20 cubic meters. The containers have a system for supplying and distributing air through the mass of compostable material present in the container. Temperatures of 50 ° C (122 ° F) are obtained after 24 hours and temperatures of 50 ° C to 60 ° C (122 ° F-140 ° F) for a period of 7 days are used to destroy the pathogenic microorganisms. U.S. Patent No. 4,392,881 describes a process for the composting of blackwater sediments occupying a two-step process. The waste material is introduced into the first closed container and continuously aerated by the bottom of the material. The material in the container is discharged from the bottom by a form that is retained in it from 7 to 14 days. The material discharged from the first container is now biologically activated; it is transferred to a second closed and aerated container in discontinuous form. The material is retained in the second container for 14 to 20 days. It is mentioned that the final product obtained can be used as animal feed. The sediments have also been arranged by means of combustion. A very rapid expansion of this technology began in the late 1950s and continued through the 1970s. The processing of blackwater sediments to be used as fuel has been described in US Patent 1,064,773 which describes a process of removing water and using raw wastewater by mixing very fine particles of activated carbon and then aerating the mixtures with oxygen-containing gas. The water content is reduced to the aerated material. This material can be pressed into pastels and used as fuel. The American patent 4, 552, 666 describes the addition of dry fall foliage or extracts thereof to sewage sludge processed into waste materials which can be formed into blocks or bricks to be used for fuel.

The American patent 4,828,577 describes a method for burning residual sediments from the waters of food product treatments. The calorific value or fuel can be increased by the addition of fillers such as sawdust. At its highest point approximately 5,060 tons per day, they are only used per day out of a total 18, 700 tons per day of solids produced in the United States by water treatment plants are burned. However, technology has declined in use at the high cost associated with sediment processing to obtain a moisture content that results in a competitive calorific value with other types of waste fuel such as anthracite coal sediments. For this reason, there is a need for an efficient and economical feasible method to produce fuels with low or sulfur-free fuels produced from biological sediments with a competitive calorific value with respect to the waste fuels currently used.

BRIEF DESCRIPTION OF THE INVENTION Expressed in a concrete form, the present invention relates to a method for producing a fuel source by sediments from biological waste. A renewable bulking agent is mixed with the sediment and the mixture is composted aerobically under effective conditions to obtain a temperature from about 77 ° C (170 ° F) to about 79 ° C (175 ° F). The temperature range of the mixture is maintained for a period of time sufficient to substantially reduce the pathogenic microorganisms and produce a compostable waste mixture with a moisture content of up to about 45%. The bulking agent is then separated from the sediment subjected to composting. The sediment subjected to separate composting has a moisture content of up to about 45% moisture and a calorific value of approximately 2,111 cal / g (3,800 Btu / lb) and is sulfur-free. The present invention relates to the combustible products produced by the method described above.

Brief description of loa D? Jaujoa The above summary, as well as the detailed description of the invention, will be more readily understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, modalities which are currently preferred are shown in the drawings; however, this invention is not limited to the arrangements and instrumentation shown. In the drawings: Fig. 1 is a schematic view of the composting method of the present invention.

Detailed Description of the Preferred Modalities The method of the present invention uses biological sediments as an initial material to produce a combustible product. The biological sediments are the sediments produced by aerobic or anaerobic conversion of carbonaceous, proteinaceous and fatty materials and / or carbohydrates, by microorganisms such as bacteria. The biological sediments used may include black water sediments such as materials produced by municipal water treatment plants or sediments originating from food processing plants. The biological sediments are concentrated by removing water at a content of about 10 to about 20% total solids before being used by the method of this invention. Additionally, the biological pellets used in the method of the invention can be mixed with animal excrements such as chickens, turkeys, cows, pigs and sheep. The method of the invention can be best described by reference to Fig. 1. A renewable bulking agent 1 is first mixed with the biological pellet 2. The bulking agent can be any water absorbing material that can be removed from the biological pellet. after the treatment by the method of this invention. Agent Suitable bulbs include flakes or would suffer from wood, peanut shells, ground corn cob, pieces of wooden pallets or yard waste, for example. Typical garden waste includes tree pruning, grass waste, leaves, vegetable waste, paper, biodegradable sheets and bags, or the like. Preferably the biological sediments or excrement pellets are mixed with the bulking agent in the radius of about one part of biological sediment and two parts of bulking matter. The mixing can be done by any applicable mechanical mixer 4 such as a continuous extraction screw. One or more of animal excrement 3 can be mixed with the sediment and the bulking agent. The mixture of the biological sediment and the bulking agent is aerobically composted under effective conditions to obtain a temperature from about 77 ° C (170 ° F) to about 79 ° C (175 ° F). Preferably, the temperature is obtained over a period of about 14 days and is maintained for an additional 7 days. The passage of aerobic composting can be conducted in any applicable annex. Preferably a composting area with dimensions of approximately 3 meters (10 feet) wide is used, approximately 1.8 to approximately 2.4 m (6 to 8 ft) tall and approximately 18.3 m (60 ft) long, for example. The effective conditions that must be obtained in a temperature range include control of the air supply to the mixture. More preferably, the composting area contains a network of perforated tubes through which the air can be forced with a fan. In the preferred particular embodiment a layer of wood flakes is sacrificed or any other bulking agent is spread over the pipe network and the bulking agent sediment mixture is placed on the surface of the layer to be wasted or sacrificed. Another layer of wood flakes or bulking agent is wasted is placed on the top surface of the bulking agent sediment mixture. The layers to be wasted provide a positive air flow through the mixture, which otherwise tends to be reduced as the mixture settles. The sacrificed layers also help control the moisture level in the mix, to prevent premature drying, and act as a filter for free airborne particles also provides a function in odor control in the composting process. Thermocouples are installed in the bulking agent sediment mixture to indicate the temperature of the mass, the air travels through the pipe network and regulates the temperature increase from about 77 ° C (170 ° F) to about 79 ° C ( 175 ° F) for a period of 14 days and then maintaining the temperature of the dough in the indicated range for approximately 7 days. These conditions are effective to substantially reduce the content of pathogenic microorganisms that are originally present in biological sediments or mixtures and droppings, to produce a treated sediment mixture that is a fuel energy product. Pathogenic microorganisms may include bacteria, viruses and parasites. A substantial reduction of pathogenic microorganisms is a reduction to a level no higher than the governmental minimums such as the Process Standards to Significantly Reduce Pathogens (PSRP) according to the Environmental Protection Agency and Processes to Reduce More Pathogens ( PFRp). After the passage of the anaerobic process is completed, the bulking agent can be separated from the combustible energy product, the separation can be made by means of a sifting 8. The bulking agent can be recycled by means of the addition to the biological sediment without treatment. The energy fuel produced to the method of the invention described above has a moisture content up to 45% and a calorific value 2,111 cal / g (3,800 Btu / lb). The produced fuel is free of sulfur, for example, no sulfur level is detected in the fuel in the fuel product, so it will not produce sulfur dioxide when it is burned. The fuel 9 is free of pathogens and can be used directly as a conventional direct product in a conventional fluidized-bed boiler or a circulating fluidized-bed boiler. The calorific value of approximately 3,889 cal / g (7,000 Btu / lb) can be obtained by drying the product at a moisture content of 12% after removing the bulking agent. Further drying can be obtained by air drying 6 for about 30 days or by rapid drying using heat 7 which can be achieved by a steam pipe dryer. The calorific value obtained by a continuous drying is equivalent to anthracite coal, fuel currently used in fluidized chamber boilers. Additionally the combustible product contains 12% moisture and can be sedimented or it can form partitions or blocks after mixing it with a binder allowed and used as boiler grade type feed. In an alternative embodiment, the method of the invention, rubber or ground rubber may be administered which is mixed with the product or fuel to provide a fuel product of 5,733 cal / g (10,320 Btu / lb).

The source of ground rubber can be car tires or trucks. Preferably the amount of rubber should not exceed the regulatory limits for sulfur emissions. The invention will now be described with reference to the following specific and non-limiting example.

Ejepplo Approximately three pounds of municipal drainage sediment obtained from the municipal water treatment plant of the city of Scranton, Pennsylvania were treated by the method of the invention. The conditions of the specific treatment are the following: A sacrificial layer of approximately 30 cm (12 in.) Thick wood chips was placed in a concrete area to be composted in the laboratory using different perforated tubes that were connected to a fan. The sediment was completely mixed with wood flakes as bulking agent. A level at the top of wood flakes with a depth of 15 cm (6 inches) was placed on top of the mixture of the sediment and the bulking agent. The mixture of the pellet was allowed to undergo composting for a period of about 7 days, where the mixture reached a temperature of about 77 ° C (170 ° F). The temperature was maintained for approximately 21 days in a range of approximately 77 ° C (170 ° F) to approximately 79 ° C (175 ° F) by blowing air (at a volume of approximately 283 liters per second (600 cubic feet / minute) ) through the mixture and the sacrificed layers when it was necessary to lower the temperature to the limits of the interval. Then, the mixture was sifted to remove the bulking agent to produce an energy fuel product. A portion of the product was dried with air in the laboratory for a few hours. Another portion of the product was dried with heat at elevated temperature for a few hours.

The approximate analysis of the resulting fuel products, according to ASTM D3172, indicates the following: No drying Drying / air Drying / heat Total Humidity (%) 25.41 2.71 0, .00 Volatile matter (%) 33 94 44 27 45 50 Fixed carbon (%) 8.40 10 96 11 27 Ash (%) 32 25 42.06 43 23 Sulfur (%) 0 00 0.00 0. .00 Total 100 00 100 00 100.00 Cal / g 2,111 2,758 2,829 (Btu / lb) 3,799 4,965 5,093 The analysis indicates that the fuel product with a moisture content of 25.41% and a calorific value of approximately 2,111 cal / g (3,800 Btu / lb) was obtained by the method of the present invention. Further drying resulted in a fuel product having a calorific value of 2,758 cal / g (4,965 Btu / lb) and 2,829 cal / g (5,093 Btu / lb). Sulfur was not detected. The present invention can be incorporated into other specific forms without apportioning the spirit or special attributes thereof according to reference s should be made to the clauses rather than the specifications as indicated in the scope of the invention.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims

REIVINPICACIQMES

1. A method for the production of a fuel energy product from biological sediments characterized in that it comprises a) mixing a renewable bulking agent with the sediments, b) completing the mixing of the first step a) under effective conditions to obtain a temperature of about 77. C (170 ° F) to about 79 ° C (175 ° F), c) maintaining the temperature of the mixture at about 77 ° C (170 ° F) to about 79 ° C (175 ° F) for a period of sufficient time to substantially reduce the pathogenic microorganisms and produce a mixture of composted products having a moisture content up to 45%; and d) separating the bulking agent from the mixture of composted sediments to produce a treated combustible waste product, which will have a calorific value of about 2,111 cal / g (3,800 Btu / lb) to 5,733 cal / g (10,300 Btu / lb).

2. The method according to claim 1, characterized in that the fuel product has the calorific value of approximately 2,111 cal / g (3,800 Btu / lb).

3. The method according to claim 1, characterized in that the energy product is free of sulfur.

4. The method according to claim 1, characterized in that the bulking agent is flakes of wood, pine shells, ground corn cob.

5. The method according to claim 1, characterized in that the renewable bulking agent is garden waste.

6. The method according to claim 1, characterized in that the ratio of sediments to the bulking agent is from about one to about two.

7. The method according to claim 1, characterized in that the biological sediment is made of sediments of black water or sediments of food products or mixtures thereof.

8. The method according to claim 7, characterized in that the biological sediment is mixed with at least one type of animal excrement.

9. The method according to claim 1, further comprising an intermediate step: c) 1) drying the treated waste to reduce the moisture content to about 12 percent, wherein the fuel product has a heating value of approximately 3,889 cal / g (7,000 Btu / lb).

10. The method according to claim 9, characterized in that it additionally comprises a step: e) sedimenting the dry waste, treated.

11. The method according to claim 9, characterized in that it additionally comprises a step of: e) forming bricks of the treated waste, dry.

12. The method according to claim 1, characterized in that the temperature is reached during a period of approximately 14 days.

13. The method according to claim 1, characterized in that the temperature is maintained for a period of about 7 days.

14. The method according to claim 1, characterized in that it additionally comprises a step of: e) mixing crushed rubber with separate treated waste, in which the combustible product has a heating value of about 5,722 cal / g (10,300 Btu / lb).

15. A combustible material prepared from animal waste by a method comprising the steps of: a) mixing a removable volume agent with animal waste; b) aerobically composing the mixture of step a) under effective conditions to obtain a temperature from about 170 ° F to about 175 ° F; c) maintaining the temperature of the mixture at about 170 ° C to about 175 ° F for a period of time sufficient to substantially reduce the pathogenic microorganisms and produce a mixture of composted waste having a moisture content of up to about 45 percent; and d) separating the bulk agent from the composted waste mixture to produce a treated animal waste combustible product, wherein the fuel product has a heating value of about 3,800 Btu / lb to about 10,300 Btu / lb. EXTRACT OF THE INVENTION. Method to produce a combustible energy product of biological sediments this proposal. A renewable bulking agent is mixed with the sediments and the mixture is aerobically composted under effective conditions that substantially reduce the level of the pathogenic microorganisms and provide a fuel product with a calorific value of approximately 2,111 cal / g (3,800 Btu / lb) after of removing the bulking agent.