CN111928270A

CN111928270A - Method for treating sugar refinery filter mud as steam power generation renewable fuel

Info

Publication number: CN111928270A
Application number: CN202010620741.5A
Authority: CN
Inventors: 韦东
Original assignee: Guangxi Guofa Energy Technology Co ltd
Current assignee: Guangxi Guofa Energy Technology Co ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2020-11-13

Abstract

The invention relates to a processing method for steam power generation by using sugar refinery filter mud as renewable fuel; in the production process of a sugar refinery, a suction filter separates filter mud from a sedimentation tank, the filter mud enters a filter mud dehydrator, bagasse with the weight ratio of 10-20% of wet filter mud is added before compression and dehydration to serve as a separation permeable medium to assist in filter mud dehydration, and the water content of the bagasse is 40% -55%; two modes are added to the bagasse, wherein the first mode comprises two times: before the first bagasse enters the suction filter, the addition amount of the bagasse is 0-5%; the second time is that the addition amount of the bagasse is 5-20% after the bagasse enters the suction filter; secondly, 10-20% of bagasse is added in one step before the dehydrator; the moisture content of the filter mud entering the filter mud dehydrator is 65-75%, the moisture content of the filter mud is 45-55% after the filter mud is dehydrated by the filter mud dehydrator, sweet water coming out of the filter mud dehydrator enters the sweet water tank, sugar remaining in 40-60% of wet filter mud can be further recycled, the filter mud dehydrated by the filter mud dehydrator enters the filter mud incinerator, steam obtained by combustion of the filter mud is provided for the steam turbine generator to generate electricity, and dust generated by combustion of the filter mud incinerator is absorbed by the dust remover.

Description

Method for treating sugar refinery filter mud as steam power generation renewable fuel

Technical Field

The invention relates to the technical field of sugar refinery filter mud treatment, in particular to a treatment method for steam power generation by using sugar refinery filter mud as renewable fuel.

Background

In the sugar production process, because non-sugar organic substances such as protein, pectin and organic acid contained in the mixed juice squeezed from the sugarcane are unfavorable for sugar boiling crystallization, the mixed juice needs to be clarified. That is, substances such as calcium hydroxide, sulfur dioxide and phosphoric acid are added to the mixed juice to precipitate non-sugar organic substances such as proteins, pectic substances and organic acids, and a residue obtained by passing the precipitate through a filter press or a vacuum suction filter is called "sludge", and is one of solid wastes of sugar factories in terms of environmental protection.

The yield of the sludge varies mainly with the conditions of the production process. At present, the clarification treatment method adopted by domestic cane sugar factories for producing white granulated sugar can be basically divided into three major types, namely a carbonic acid method, a sulfurous acid method and a lime method. The common sulfurous acid method has less ash adding amount, and the filter mud amount (absolutely dry, the same below) accounts for 0.7 to 1.4 of the sugarcane squeezing amount; the carbonic acid method has large ash adding amount, and the amount of filter mud accounts for 4.5 to 5.0 percent of the sugarcane squeezing amount; the lime method only uses lime as a clarifying agent, so that the amount of filter mud generated is the least, and accounts for 0.5-1.0% of the amount of squeezed sugarcane.

The composition of the sludge varies from one production process to another. The ash adding amount of the filter mud obtained by the sulfurous acid method is small, the filter mud does not contain a large amount of calcium salt, the total amount of organic matters in dry matters can reach about 80%, and the organic matters mainly comprise 5-14% of lipoid (cane wax and cane fat), 15-30% of fiber, 5-15% of sugar, 5-15% of crude protein and 9-20% of total ash content. The lime method filter mud has similar components to the sulfurous acid method, and the total ash content is slightly lower than that of the sulfurous acid method and is about 5-10%. The content of CaCO3 in the dry product of the carbonic acid method filter mud is about 70-80%, the components are mainly inorganic substances, and the content of organic substances is about 15%.

The organic matter content of the filter mud of the sulfurous acid method and the lime method is high, the filter mud can be used as a base fertilizer of the sugarcane after being stacked and fermented, the labor cost is greatly improved along with the development of the society, and the filter mud used by farmers as the fertilizer has large use amount and high labor cost, so the enthusiasm of the farmers as the fertilizer is reduced year by year, the filter mud can not be timely returned to the field for treatment, a great risk source of environmental pollution is formed, and great pressure is brought to sugar factories and the environment, so the filter mud treatment problem becomes more and more urgent. A new filter mud treatment mode is required to achieve the effects of stabilization, harmlessness, reduction and recycling.

Disclosure of Invention

The present invention is to solve the above problems in the background art, and an object of the present invention is to provide a method for processing sugar mill sludge as a renewable fuel for steam power generation.

In order to achieve the above object, the present invention provides a technical solution,

a treatment method for performing steam power generation by using filter mud of a sugar refinery as renewable fuel comprises the following steps that in the production process of the sugar refinery, a suction filter separates the filter mud from a sedimentation tank, the filter mud enters a filter mud dehydrator, bagasse with the wet filter mud ratio of 10-20% is added before compression and dehydration to serve as a separation water-permeable medium to assist in filter mud dehydration, and the water content of the bagasse is 40% -55%; the bagasse addition is divided into two times: before the first bagasse enters the suction filter, the addition amount of the bagasse is 0-5%; the second time is that the addition amount of the bagasse is 5-20% after the bagasse enters the suction filter;

the moisture content of wet filter mud entering the filter mud dehydrator is 65-75%, after the wet filter mud is dehydrated by the filter mud dehydrator, the moisture content of press-dried filter mud is 45-55%, sweet water coming out of the filter mud dehydrator enters the sweet water tank, sugar remained at 40-60% of the wet filter mud can be further recovered, after the filter mud dehydrated by the filter mud dehydrator enters the filter mud incinerator, steam obtained by combustion of the filter mud is provided for the turbine generator to generate electricity, and dust generated by combustion of the filter mud incinerator is absorbed by the dust remover.

Further, the wet sludge before passing through the sludge dehydrator contains 65-75% of water, and the weight ratio of the sludge to the cane is as follows: 3.5 to 4.5 percent, and the water content of the press-dried filter mud is reduced to 45 to 55 percent after the filter mud is dehydrated by a filter mud dehydrator.

In one embodiment of the present invention, the sweet water from the filter mud dehydrator is returned to the hot water tank for pressing and mixed with hot water, and the sweet water is used as permeate water of the last two presses to further recover sweet water sugar by pressing of the last two presses.

As another embodiment of the invention, the sweet water from the sweet water tank returns to the sedimentation tank to continue separating the filter mud.

Furthermore, the suction filter is a vacuum suction filter, wet filter mud separated by the vacuum suction filter is conveyed to a new loading and conveying belt by an original filter mud conveying belt and then to a feeding valve of the mixer, the feeding valve conveys the wet filter mud to the filter mud dehydrator to obtain press-dried filter mud, the press-dried filter mud is conveyed to an original combustion furnace feeder by a filter mud conveying system, and finally the press-dried filter mud enters the filter mud incinerator to be burned.

Further, the mud filter gets into the sediment pipe from scraper blade machine before former stove, and after getting into boiler batcher again, through spouting the broadcast ware, reentrant boiler fluidized bed, the mud filter gets into boiler furnace through boiler fluidized bed and burns, and the mud filter through boiler furnace burning passes through the over heater again, convection current pipe, economizer, air heater, dust remover and discharges from the chimney at last, still includes that primary air fan gives air heater air supply, then gives through the hot-blast main and spouts broadcast ware and boiler fluidized bed and supply heat.

Compared with the prior art, the invention has the beneficial effects that:

by adopting the treatment method, part of sugar in the filter mud can be recovered from the filter mud dehydrated by the filter mud dehydrator; when the filter mud is incinerated in the filter mud incinerator, the volume of the generated ash slag is greatly reduced; meanwhile, the filter mud is burnt in the filter mud incinerator to provide steam for a steam turbine generator and places needing the steam industrially; in addition, combustion ash is collected by adopting a cloth bag or an electrostatic dust collector, so that the composite fertilizer is used for producing the composite fertilizer, the storage time is long, and pollution is avoided. The invention can recover the sugar in the filter mud, the filter mud is burnt, the problems of pollution of soil, waste water and waste gas generated by stacking and retaining the filter mud are solved, the volume of generated ash is greatly reduced, and the steam generated by burning the filter mud can be provided for power plants and industries for use.

Drawings

FIG. 1 is a schematic structural diagram of one embodiment of a process for steam power generation using sugar mill sludge as a renewable fuel according to the present invention;

FIG. 2 is a schematic structural diagram of another embodiment of the process for steam power generation using sugar mill sludge as a renewable fuel according to the present invention;

FIG. 3 is a flow chart of the pretreatment method of the filter mud for steam power generation by using the sugar refinery filter mud as renewable fuel.

FIG. 4 is a flow chart of the combustion process of the filter mud for the treatment of steam power generation by using the sugar refinery filter mud as a renewable fuel.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, 2, 3 and 4, the invention provides a method for processing sugar mill filter mud as renewable fuel for steam power generation;

in the production process of a sugar refinery, the neutralization juice enters a sedimentation tank, filter mud is sucked out from the sedimentation tank, the sucked filter mud enters a filter mud dehydrator, the moisture content of wet filter mud entering the filter mud dehydrator is 65-75%, the filter mud is dehydrated by a filter mud press-drying dehydrator, the moisture content of the press-dried filter mud is 45-55%, sweet water from the filter mud dehydrator enters a sweet water tank, and then is pumped back to the original process, and the steps are repeated again; in which the sweet water separated by the filter press is pumped to the previous pressing process, as one embodiment of the present invention, as shown in fig. 2, the sweet water from the sweet water tank returns to the hot water tank for pressing and is mixed with hot water, in one way, the sweet water is used as the permeate water of the last press, and the sweet water sugar is further recovered by pressing of the last press; another way is to further recover sweet water sugar by squeezing with a penultimate squeezer as the permeate water before the penultimate squeezer.

In the present invention, there are two ways to add bagasse:

1. the obtained effect is best by adding the components in two times: before the first bagasse enters the suction filter, the addition amount of the bagasse is 0-5%; the second time is that the addition amount of the bagasse is 5-20% after the bagasse enters the suction filter;

2. the bagasse may be added after the suction filter has separated the sludge from the sedimentation tank, but the effect obtained is inferior to that of the first step.

As another embodiment of the present invention, referring to fig. 1, the sweet water separated from the filter press is returned to the settling tank.

And the filter mud dehydrated by the filter mud dehydrator enters a filter mud incinerator, steam obtained by combustion of the filter mud is supplied to a turbine generator for power generation, and dust generated by combustion of the filter mud incinerator is absorbed by a dust remover. The wet filter mud from the suction filter contains 65-75% of water, and the filter mud with 45-55% of water can be obtained by adding part of bagasse, mixing, and dehydrating through a filter mud dehydrator. The dewatered filter mud can be sent to a fluidized bed incinerator for combustion by a belt conveyor, the filter mud rolls and is dried and combusted in a combustion fluidized bed in a boiling state, fly ash is carried to a hearth outlet by flue gas to complete combustion, the high-temperature flue gas heats each heated surface of a boiler to generate steam, the steam is sent to a steam turbine for power generation, back pressure steam is sent to a process, and ash residues are recovered to be used as fertilizer.

Because the moisture of the wet filter mud separated by the suction filter reaches 65-75 percent, and the wet filter mud is not resistant to extrusion, the moisture is difficult to be directly extruded and separated by the traditional mechanical dehydration method, the combustion effect is influenced, and the energy utilization rate is low; therefore, the bagasse is added and mixed, and then the mixture is dewatered by a filter mud dewatering machine, and the press-dried filter mud with the moisture of 45-55% can be obtained.

The wet filter mud has large water content, high ash content and lower heat value, is difficult to catch fire compared with bagasse, and has the alkali metal content far higher than that of the bagasse, so that ash is easily accumulated on a heating surface to block a flue; therefore, the fluidized bed boiler is used for combustion, and the characteristics of difficult ignition and easy dust accumulation of the combustion filter mud are fully considered structurally; the low-temperature fire-through technology and the on-line ash removal measure are applied.

When the bagasse is not added into the filter mud produced in the sugar preparation process by the sulfurous acid method, the water content is the same as 50%, and the calorific value of the filter mud is about 80% of that of the bagasse. 10-20% of bagasse is added into the wet filter mud, and after the wet filter mud is dehydrated to reach 50% of water, the filter mud heat value of the mixed bagasse is equal to 85% of the bagasse heat value. The same 50% water content of the filter mud produced in the lime process has a calorific value slightly higher than that of bagasse, and the filter mud with the water content lower than 50% has a combustion value.

Referring to fig. 3, the suction filter is a vacuum suction filter, the filtered mud sucked out by the vacuum suction filter is conveyed from an original filtered mud conveying belt to a new loading and conveying belt and then to a mixer to a feeding valve, the feeding valve is conveyed to a filtered mud dehydrator to obtain press-dried filtered mud, the press-dried filtered mud enters a boiler feeder from a filtered mud conveying system and finally enters a filtered mud incinerator for incineration, and sweet water generated in the process of press-drying the filtered mud by the filtered mud dehydrator enters a sweet water tank;

as one specific embodiment of the invention: 3 sludge dewaterers are used for sludge pretreatment, and a press dryer is arranged in front of an original 2# boiler; the filtered mud is transferred to a newly-loaded filtered mud transfer belt by a discharger from the position of an original conveying belt close to a boiler room, and is obliquely lifted to be conveyed to a filtered mud bagasse mixing box above a filtered mud dehydrator, and a stirrer is arranged in the mixing box; distributing a small amount of bagasse from a bagasse conveying system before an original furnace to a positive displacement metering scale, and putting the weighed bagasse into a sludge-filtering bagasse mixing box; the filtered bagasse is uniformly stirred and mixed in a mixing box through a stirrer, and is delivered to 3 sludge-filtering dewaterers through a feeding valve, the mixture of the filtered bagasse is compressed in a press dryer, sweet water flows out of sieve pores, the sweet water is collected in a sweet water tank, and is delivered back to a sedimentation tank by a centrifugal pump; and (3) pressing the filter residues to 50% of water, discharging the filter residues to a dry filter mud conveyer belt, conveying the filter mud to a filter mud elevator, conveying the filter mud to an original front-furnace scraper machine by the elevator, and opening a feed opening of the original front-furnace scraper machine to be large enough to ensure that all the filter mud falls into a No. 3 boiler for combustion.

Referring to fig. 4, the filtered mud enters the slag falling pipe from the original furnace front scraper, then enters the boiler feeder, passes through the spray seeding device, and then enters the boiler fluidized bed, the filtered mud enters the boiler furnace for combustion after passing through the boiler fluidized bed, the filtered mud combusted by the boiler furnace passes through the superheater, the convection pipe, the economizer, the air preheater and the dust remover and is finally discharged from the chimney, the air supply device further comprises a primary fan for supplying air to the air preheater, and then the heat supply device supplies heat to the spray seeding device and the boiler fluidized bed through a hot air pipe.

The convection heating surface of the double-drum boiler is not beneficial to ash removal, the possibility of ash blockage is high, and the double-drum boiler is not very suitable for burning filter mud of a sugar refinery; however, in order to reduce the technical improvement capital pressure, the 3# boiler can be used for modification under the conditions of perfecting the corresponding ash removal facility and increasing the ash removal frequency, the boiler can basically continuously run for a cleaning period, and the accumulated ash on the heated area needs to be completely cleaned during the machine cleaning period. The dry filter mud slips to a spray sowing device through a feeder, is blown into a fluidized bed by spray sowing air, is blown up by high-speed furnace bottom air, is rolled, dried and burned in a combustion fluidized bed in a boiling state, is further mixed with secondary air at the upper part of the fluidized bed, fly ash is carried by flue gas to the front of a hearth outlet to complete combustion, the high-temperature flue gas heats each heating surface of a boiler to generate steam, and finally the steam is sent out of a chimney after dust removal.

Therefore, the original fire grate and the air chamber are changed into the fluidized bed and the air chamber thereof, slag is not discharged from the bottom of the furnace, and the cross section of the fire grate is improved; the height of the heat insulation section at the lower part of the hearth is reset, so that the stable combustion temperature is ensured; pulse ash cleaners are arranged at the positions of the superheater, the convection tube and the economizer to ensure effective ash removal; air duct reconstruction; flue reconstruction: flue gas treatment: the original water film dust removal system is temporarily utilized, and the bag dust removal is not changed temporarily. □

When the bagasse is not added into the filter mud produced in the sugar preparation process by the sulfurous acid method, the water content is the same as 50%, and the calorific value of the filter mud is about 80% of that of the bagasse. 10-20% of bagasse is added into the wet filter mud, and after the wet filter mud is dehydrated to reach 50% of water, the filter mud heat value of the mixed bagasse is equal to 85% of the bagasse heat value. The filter mud produced in the lime method sugar preparation process has the same 50% of water content, the calorific value of the filter mud is slightly higher than that of bagasse, and the filter mud with the water content of about 50% has the combustion value. The tested sludge and bagasse were fresh sludge and bagasse, and were not stored in a stack, and the low calorific value test of bagasse was close to the empirically calculated LCV ═ 18260-207.63 (% bagasse moisture) — 182.6 (% ash) — 31.14 (% sugar)]kJ.kg^-1。

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.

Claims

1. The treatment method for performing steam power generation by using the sugar refinery filter mud as renewable fuel is characterized by comprising the following steps: in the production process of a sugar refinery, a suction filter separates filter mud from a sedimentation tank, the filter mud enters a filter mud dehydrator, bagasse with the weight ratio of 10-20% of wet filter mud is added before compression and dehydration to serve as a separation permeable medium to assist in filter mud dehydration, and the water content of the bagasse is 40% -55%; the bagasse is added in two ways, wherein the first way is that the bagasse is added in two times: before the first bagasse enters the suction filter, the addition amount of the bagasse is 0-5%; the second time is that the addition amount of the bagasse is 5-20% after the bagasse enters the suction filter; the second method is to add 10-20% of bagasse in one step before the press dryer.

The moisture content of wet filter mud entering the filter mud dehydrator is 65-75%, the moisture content of the filter mud is 45-55% after the filter mud is dehydrated by the filter mud dehydrator, sweet water coming out of the filter mud dehydrator enters the sweet water tank, sugar remaining in 40-60% of the wet filter mud can be further recovered, the filter mud dehydrated by the filter mud dehydrator enters the filter mud incinerator, steam obtained by combustion of the filter mud is provided for the steam turbine generator to generate electricity, and dust generated by combustion of the filter mud incinerator is absorbed by the dust remover.

2. The process for steam power generation of sugar mill sludge as renewable fuel according to claim 1, characterized in that: the wet filter mud before passing through the filter mud dehydrator contains 65-75% of water, and the weight of the wet filter mud to the sugarcane ratio is as follows: 3.5-4.5%, and the water content of the filter mud is 45-55% after dehydration.

3. The process for steam power generation of sugar mill sludge as renewable fuel according to claim 1, characterized in that: and the sweet water from the sweet water tank returns to the squeezing hot water tank in the previous flow to be mixed with hot water to be used as the penetrating water of two last squeezing machines, and sweet water sugar is further recovered through squeezing of the squeezing machines.

4. The process for steam power generation of sugar mill sludge as renewable fuel according to claim 1, characterized in that: and returning the sweet water from the sweet water tank to a sedimentation tank to continuously separate filter mud.

5. The process for steam power generation of sugar mill sludge as renewable fuel according to claim 1, characterized in that: the suction filter is a vacuum suction filter, wet filter mud separated by the vacuum suction filter is conveyed to a new loading transfer belt from an original filter mud conveying belt and then to a mixer to a feeding valve, the feeding valve conveys the wet filter mud to a filter mud dehydrator to obtain press-dried filter mud, the press-dried filter mud is conveyed to an original combustion furnace feeder by a filter mud conveying system, and finally the press-dried filter mud enters a filter mud incinerator to be incinerated.

6. The process for steam power generation of sugar mill sludge as renewable fuel according to claim 5, characterized in that: the filter mud gets into the sediment pipe from scraper conveyor before former stove, and after getting into boiler batcher again, through spouting the broadcast ware, reentrant boiler fluidized bed, the filter mud gets into boiler furnace behind boiler fluidized bed and burns, and the filter mud that burns through boiler furnace passes through over heater, convection current pipe, economizer, air heater, dust remover and discharges from the chimney at last, still includes that primary air fan supplies air for air heater, then gives through the hot-blast main and spouts broadcast ware and boiler fluidized bed and supply heat.