TECHNICAL FIELD OF THE INVENTION:

The present invention relates to the field of green chemistry and particularly to a bio pesticide generator plant for generating bio pesticide from the carbon dioxide containing flue gas.

BACKGROUND OF THE INVENTION:

Carbon dioxide is the main greenhouse gas emitted through human activities. Since the Industrial revolution the amount of CO ₂ has increased by 40% in the atmosphere to nearly 400ppm. Carbon dioxide is heavier than air and hence, its concentration is high near the earth’s surface. It has the ability to traps heat and hence, the rise in CO ₂ emissions is the cause for the rise in earth’s surface temperature. This has resulted in steady decrease in the polar ice volumes over the decades. A further decrease will result in sea level rise to such an extent that low lying countries like Maldives, Mauritius and Netherlands may drown. Thus control of carbon dioxide emissions is not a regional requirement but a global need.

Currently carbon capture and storage (CCS) technologies are being researched extensively throughout the western world. Carbon dioxide is sequestered into oil wells to extract maximum amount crude oil or natural gas. The incoming carbon dioxide pushes the fossil fuel upwards and hence, it is easier to extract them out. CO ₂ is also being pumped in defunct oil wells and coalmines. But this is just a method of hiding away the greenhouse gas and not a way of addressing the issue. A structural defect or crack may lead to massive leakage of the stored gas. Thus the nearby area will experience a sudden drop in concentration of oxygen making the region inhospitable. Hence, a long term solution to the CO ₂ conversion into other products. Carbon dioxide is a very stable molecule and most carbon dioxide treating technologies considerable require of energy. This has prevented many technologies remaining in the laboratory or pilot scale level only. It is critical that economically viable technology for treating carbon dioxide be developed.

Some are researches in which a reduced dose of fungicide is mixed with bicarbonate to get rid of the plant diseases. The table below is a compilation of both pre- and post harvest fungal treatment strategies that have used bicarbonate. Below is a list of agricultural fungal diseases for which sodium/potassium bicarbonate treatment has been reported in research literature. Bicarbonate salt is mixed with other mineral or biological extracts in many of the researches. Few are researches in which a combination of microorganisms and bicarbonate has been studied for curing fruit diseases.

References details for further reading:

Present invention provides a technology where carbon dioxide is converted to the bio pesticide. The product obtained is also an important industrial raw material and is used in a range of industries from desulfurization of flue gas to toothpastes. The product has also been found to be useful in killing fungal diseases occurring on agricultural crops. As it causes no harmful effect to humans and the environment, it has been categorized as a biopesticide. Thus the product can be sold to farmers to for use in their fields instead of chemical fungicides. Adoption of this technology can result in dual benefits of reduction of carbon dioxide emissions and reduction of chemical pesticides polluting our water resources.

SUMMARY OF THE INVENTION:

In its main aspect, present invention provides a bio pesticide generator plant to generate the bio pesticide from the carbon dioxide containing flue gas comprising a. a flue gas receptor with an optional flue gas filter; and b. a reactor having a bottom portion holding an aqueous alkali metal carbonate or hydroxide solution, a top portion filled with structured packing, a liquid transporter system for transporting the aqueous alkali metal carbonate or hydroxide solution from said bottom portion to said top portion for saturating the structural packing, and an outlet for collecting the generated alkali metal bicarbonate bio pesticide; characterized in that the flue gas receptor is fitted to the source of flue gas to deliver the carbon dioxide containing flue gas to the bottom portion of said reactor for bubbling through the aqueous alkali metal carbonate or hydroxide solution and then to travel upward within the top portion by passing through the structured packing saturated with aqueous alkali metal carbonate or hydroxide solution for generating the alkali metal bicarbonate bio pesticide.

In another aspect, it provides a bio pesticide generator plant to generate the bio pesticide from the carbon dioxide containing flue gas comprising a. a flue gas receptor with an optional flue gas filter; b. a reactor having a bottom portion holding an aqueous alkali metal carbonate or hydroxide solution, a top portion filled with structured packing, a liquid transporter system for transporting the aqueous alkali metal carbonate or hydroxide solution from said bottom portion to said top portion for saturating the structural packing, and an outlet for collecting the generated alkali metal bicarbonate bio pesticide; c. rotary dissolver for dissolving the alkali metal carbonate or hydroxide in water and supplying the aqueous alkali metal carbonate or hydroxide solution to said reactor, optionally having a filter to remove particulate matter from the aqueous alkali metal carbonate or hydroxide solution before supplying it to the reactor; and d. a centrifuge connected to the outlet of said reactor to receive the aqueous alkali metal carbonate or hydroxide solution, aqueous alkali metal bicarbonate solution and alkali metal bicarbonate crystals and separate the crystals from aqueous solutions; characterized in that the rotary dissolver supply the aqueous alkali metal carbonate or hydroxide solution to the bottom portion of said reactor; the supplied aqueous alkali metal carbonate or hydroxide solution is transported from said bottom portion to said top portion using the liquid transporting system for saturating the structural packing; the flue gas receptor is fitted to the source of flue gas to deliver the carbon dioxide containing flue gas to the bottom portion of said reactor for bubbling through the aqueous alkali metal carbonate or hydroxide solution and then to travel upward within the top portion by passing through the structured packing saturated with aqueous alkali metal carbonate or hydroxide solution for generating the alkali metal bicarbonate bio pesticide which is collected as an aqueous alkali metal bicarbonate solution or alkali metal bicarbonate crystals from the centrifuge connected to the outlet of said reactor.

BRIEF DISCRIPTION OF ACCOMPANYING DRAWINGS:

The embodiments herein will be better understood from the following detailed description with reference to the drawings, in which the reference numerals indicate:

FIG 1 illustrates sectional view of a bio pesticide generator plant according to the first aspect of present invention;

FIG 2 illustrates the scheme for generating alkali metal bicarbonate from flue gas emitted from biogas plant using a bio pesticide generator plant according to the present invention; FIG 3 illustrates the scheme for generating alkali metal bicarbonate from flue gas emitted from brewery plant using a bio pesticide generator plant according to the present invention;

FIG 4 illustrates the scheme for generating alkali metal bicarbonate from flue gas emitted from biomass combustion plant using a bio pesticide generator plant according to the present invention;

FIG 5 illustrates the scheme for generating alkali metal bicarbonate from flue gas using a bio pesticide generator plant and various other accessories to separate out the crystals of alkali metal bicarbonate and also recycling the filtrate obtained after centrifugation according to the present invention;

DETAILED DESCRIPTION OF THE INVENTION:

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. To facilitate the understanding of this invention, a number of terms are defined below. Terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as "a", "an" and "the" are not intended to refer to only a singular entity; but include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage, does not delimit the invention, except as outlined in the claims.

Biopesticides are agricultural pest antagonists that have been derived from natural materials like plants, microorganisms, animals and minerals. Biopesticides are becoming increasingly popular, as they are safer towards environment and human consumption than traditional biopesticides. For agricultural produce to be labelled ‘organic’, only biopesticides can be used to kill pathogens and insects that eat the plants. Biopesticides are also more target specific than traditional chemical pesticides. They decompose quickly and do not leave problematic residues. Hence, biopesticide usage is being promoted all over the world. The biopesticide worldwide usage is expected to grow at 12% CAGR from $2.1 billion in 2012 to $3.7 billion in 2017 and currently for 4.5% of the world pesticide market. North America 40% of the biopesticides produced followed by Europe and Oceania continent with 20% each respectively.

The present invention relates to a bio pesticide generator plant to generate the bio pesticide from the carbon dioxide containing flue gas.

According to the first aspect of the present invention, a bio pesticide generator plant to generate the bio pesticide from the carbon dioxide containing flue gas comprises a. a flue gas receptor with an optional flue gas filter; and b. a reactor having a bottom portion holding an aqueous alkali metal carbonate or hydroxide solution, a top portion filled with structured packing, a liquid transporter system for transporting the aqueous alkali metal carbonate or hydroxide solution from said bottom portion to said top portion for saturating the structural packing, and an outlet for collecting the generated alkali metal bicarbonate bio pesticide; characterized in that the flue gas receptor is fitted to the source of flue gas to deliver the carbon dioxide containing flue gas to the bottom portion of said reactor for bubbling through the aqueous alkali metal carbonate or hydroxide solution and then to travel upward within the top portion by passing through the structured packing saturated with aqueous alkali metal carbonate or hydroxide solution for generating the alkali metal bicarbonate bio pesticide. Refer figure 1 for explanation. According to another aspect, a bio pesticide generator plant to generate the bio pesticide from the carbon dioxide containing flue gas comprises a. a flue gas receptor with an optional flue gas filter; b. a reactor having a bottom portion holding an aqueous alkali metal carbonate or hydroxide solution, a top portion filled with structured packing, a liquid transporter system for transporting the aqueous alkali metal carbonate or hydroxide solution from said bottom portion to said top portion for saturating the structural packing, and an outlet for collecting the generated alkali metal bicarbonate bio pesticide; c. rotary dissolver for dissolving the alkali metal carbonate or hydroxide in water and supplying the aqueous alkali metal carbonate or hydroxide solution to said reactor, optionally having a filter to remove particulate matter from the aqueous alkali metal carbonate or hydroxide solution before supplying it to the reactor; and d. a centrifuge connected to the outlet of said reactor to receive the aqueous alkali metal carbonate or hydroxide solution, aqueous alkali metal bicarbonate solution and alkali metal bicarbonate crystals and separate the crystals from aqueous solutions; characterized in that the rotary dissolver supply the aqueous alkali metal carbonate or hydroxide solution to the bottom portion of said reactor; the supplied aqueous alkali metal carbonate or hydroxide solution is transported from said bottom portion to said top portion using the liquid transporting system for saturating the structural packing; the flue gas receptor is fitted to the source of flue gas to deliver the carbon dioxide containing flue gas to the bottom portion of said reactor for bubbling through the aqueous alkali metal carbonate or hydroxide solution and then to travel upward within the top portion by passing through the structured packing saturated with aqueous alkali metal carbonate or hydroxide solution for generating the alkali metal bicarbonate bio pesticide which is collected as an aqueous alkali metal bicarbonate solution or alkali metal bicarbonate crystals from the centrifuge connected to the outlet of said reactor. Refer figure 5 for explanation.

In both the aspects, there may be various flue gas sources which contain carbon dioxide. The flue gas from some sources may need to be filtered to remove the unwanted or hazardous gases.

In one such embodiment, the flue gas source is the exhaust gas emitted from biogas plant. The hydrogen sulphide is one of the component present in the flue gas emitted from the biogas plant. Thus, it is preferable that the bio pesticide generator plant contain the flue gas filter to separate the hydrogen sulphide from the flue gas. One such example of filter is a hydrogen sulphide scrubber. More preferably said hydrogen sulphide scrubber is an aqueous sodium bicarbonate solution. Refer figure 2 for explanation.

In another embodiment, the flue gas source is the exhaust gas emitted from breweries. Mostly the exhaust gas from breweries contain nitrogen, carbon dioxide, water vapor and unreacted oxygen. This carbon dioxide can be directly used in the bio pesticide generator plant. Thus, in such cases the flue gas receptor delivers the carbon dioxide containing flue gas to the bottom portion without filtering it. Refer figure 3 for explanation.

In yet another embodiment, the flue gas source is the exhaust gas emitted from biomass combustion plant. The unburnt carbon and ash particles are seen to be present in the flue gas emitted from the biomass combustion plant. Thus, it is preferable that the bio pesticide generator plant contain the flue gas filter to separate unburnt carbon and ash particles from the flue gas. One such example of filter is a cyclone separator. Refer figure 4 for explanation. The structured packing is embossed sheet of metal perforated and given a complicated shape thereby forming relatively honeycomb like structure, this allows larger surface area for increased residence of flue gas passing through the reactor. At the same time, it maximizes the liquid spreading. Alternatively wire mesh, embossed sheet and wire gauze or other suitable materials can be used to prepare such packing which work on similar mechanism and deliver similar kind of results.

The liquid transporter system is anything which can transport the aqueous alkali metal carbonate or hydroxide solution from the bottom portion of the reactor to the top portion of the reactor. It keep replacing the aqueous alkali metal carbonate or hydroxide solution in structured packing. This increase the efficiency of the rector as aqueous alkali metal carbonate or hydroxide solution can be re-circulated in the system i.e. reactor till maximum of it get converted to alkali metal bicarbonate by continuously reacting with the carbon dioxide. Preferably a bypass pipe and a pump can be used as liquid transporter system for such transportation of the aqueous alkali metal carbonate or hydroxide solution from bottom portion to top portion of the reactor.

Most suitably the alkali metal carbonate is selected from sodium carbonate and potassium carbonate and accordingly the alkali metal bicarbonate bio pesticide obtained is sodium bicarbonate or potassium bicarbonate. It can be in the aqueous solution form, aqueous slurry form or solid crystals form.

Sodium bicarbonate or potassium bicarbonate are the superior bio pesticides for various reasons. Chemical fungicides are costly, some costing thousands of rupees per kg. To cure a fungal attack, the farmer needs to spray the fungicide on the entire plant and not just the diseased area. Fungi spores are spread through air. So all crops near a diseased plant are susceptible to the attack. Thus, it becomes very costly to treat fungal diseases. Hence, farmers use them only when the crop is under attack. But no effort was taken earlier to prevent a fungal attack. Sodium bicarbonate is a much cheaper fungicide. It is very effective as a preventive measure against fungal diseases. Thus crops can be economically fortified against fungal diseases by a spray of sodium bicarbonate biopesticide.

Environment Protection Agency (EPA), United States has granted sodium bicarbonate the status of a biopesticide. Sodium bicarbonate is found in nature in a mineral called trona. It is used extensively in cooking in the form of baking soda. Bicarbonate has been shown to have anti-cancer activity, curative action against human fungal infection, for oral hygiene as a component of toothpaste and mouthwash among other applications. Bicarbonates have been shown to have a fungicidal effect on agricultural produce. Sodium bicarbonate is being used to treat fungal attack in home gardens. Sodium and potassium bicarbonates are environment and human friendly chemicals. They pose no long-term hazards to human or animal health as some pesticides do. Hence, EPA has registered sodium and potassium bicarbonates as biopesticides.

Workers who spray pesticides look for ease of usage. Sodium bicarbonate dissolves easily in water. Vessels utilized for making the solution need to be just washed with soap after which even food can be cooked in it. Sodium bicarbonate causes no harm on inhalation or exposure to skin. It can be easily washed off the body. Fruits and vegetables can be consumed even one hour after they were sprayed with sodium bicarbonate. Organically cultivated agricultural crops are in great demand in Europe and North America. Agricultural produce labelled organic command higher export price than regular produce. Pesticides categorized as ‘biopesticides’ are only allowed to treat plant diseases for the produce to be certified organic. Thus sodium bicarbonate, a product registered by EPA as a biopesticide, would be ideal for use in organic farming. It is estimated that Indian agricultural export valued at Rs. 4000 crore gets rejected every year due to presence of high concentration of pesticides or use of banned pesticides.

Fruits and leaves are slightly acidic and fungi have adapted to this. Hence, fungi need a pH between 5-6 to thrive. Sodium bicarbonate is slightly alkaline. Thus a spray of sodium bicarbonate changes the pH of the surface of the fmits and vegetables making it slightly alkaline. This is not suitable for fungal infection. The sodium ions also help in breaking the cell walls of the fungi thus killing them. This is the mechanism how sodium bicarbonate protects plants against fungal diseases.

The present invention is further described with the help of the following examples, which are given by way of illustration and should not be construed to limit the scope of the invention in any manner.

EXAMPLES:

Example 1: bio pesticide generator plant for biogas plant

The 18-inch ID MS pipe was installed as flue gas receptor at the biogas plant emission vent. A ¾S scrubber was fitted to said pipe for filtering the flue gas and pass CO ₂ to the reactor. The 5000 Kg reactor was used. The bottom portion was filled with 1500 ltrs of sodium hydroxide and 1500 Kg of water in 1:1 ratio. The “350Y” M ² /M ³ was used as structured packing. Volume of structured packing in pipe being used was 9.27 M ³ . The 8 inch ODMS bypass pipe and a 3hp centrifugal pump was used to transport the aqueous sodium hydroxide/carbonate solution from bottom portion to top portion of the reactor. The flue gas containing 13.88 kg of CO ₂ per hour was passed through the reactor for 72 hrs. This is a 2 stage reaction when PH is less than 8, CO ₂ first react with water to form carbonic acid and slowly the acid formed then reacts with alkali to give NaHCO ₃ After confirming the concentration of sodium bicarbonate solution (NaHCO ₃ +H ₂ O) to be fully saturated bicarbonate solution then the solution was taken out to pack as aqueous solution of sodium bicarbonate as bio pesticide. Total weight of the material taken out was 3240 kg.

Example 2: bio pesticide generator plant for breweries

The 20-inch ID MS pipe was installed as flue gas receptor at the brewery emission vent. The 5000/kg MS reactor was used. The bottom portion of reactor was filled with 1500 kg of water and 1500 kg of sodium hydroxide. The “350Y” 19.5-inch of OD was used as structured packing. Standard area of structured packing used was 350 M ² /M ³ . The percentage of increase in volume due to structured packing -1250%. The 4-inch ID MS bypass pipe and a 3 hp centrifugal pump was used to transport the aqueous sodium hydroxide/carbonate solution from bottom portion to top portion of the reactor. The flue gas containing 13.88kg of CO ₂ was passed through the reactor. The sodium bicarbonate bio pesticide was removed from the reactor after confirming fully saturated bicarbonate solution in slurry form. The weight of slurry obtained was 3240 kg.

Example 3: bio pesticide generator plant for biomass combustion plant

The 20-inch ID MS pipe was installed as flue gas receptor at the biomass combustion plant emission vent. A cyclone separator was fitted to said pipe for filtering the flue gas, remove unburnt carbon and ash particles and pass CO ₂ to the reactor. The 5000 kg MS reactor was used. The bottom portion was filled with 1500 kg of water and 1500 kg sodium hydroxide in 1:1 ratio. The Type “350Y” 19.5 inch of OD was used as structured packing. Standard area of structured packing used 350M ² /M ³ . The percentage of increase in Volume due to structured packing -1250%. The 6-inch ID MS bypass pipe and a 5Hp centrifugal pump was used to transport the aqueous sodium carbonate solution from bottom portion to top portion of the reactor. The 33% in volume of flue gas containing 13.88 kg of CO ₂ was passed through the reactor for 72 hrs. After confirming the concentration of sodium bicarbonate solution in the reactor to be fully saturated bicarbonate solution. The solution was taken out and supplied to the pusher centrifuge to get 30% of solid crystals of sodium bicarbonate bio pesticide and aqueous solution of sodium bicarbonate bio pesticide. Total weight of the material along with the crystals and the aqueous solution was 3240 kg. Examples 4, 5 and 6:

Same bio pesticide generator plants as in examples 1, 2 and 3 were used with ratio of 1:1 potassium hydroxide solution (1500 Kg of potassium hydroxide 1500 kg of water with 13.88 kg of CO ₂ /Per hr) to get potassium bicarbonate bio pesticide in following forms and quantities: