FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
IMPROVED METHOD FOR GENERATING STEAM FROM DISTILLERY WASTE
THERMAX LIMITED
an Indian Company
Chinchwad, Pune411 019, Maharashtra, India
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.
1

FIELD OF INVENTION
This invention relates to an improved method for generating steam from waste such as concentrated distillery waste (spentwash).
PRIOR ART:
It is known to use spent wash, which is a distillery waste (effluent) for the purpose of generation of biogas, which can be used, for producing steam.
Spentwash is a process waste and as per the pollution norms, is required to be treated to bring down its Biological oxygen demand / Chemical oxygen demand (BOD / COD) levels as well as colour to an acceptable level so that the same can be discharged on land or in water bodies. Another way of disposing spentwash is to incinerate it and therefore ensuring complete combustion of organics.
Presently, no known technology exists which feasibly meets the norms for disposal of this distillery waste. Technologies like biomethanation are available, which are practiced normally, and make a partial treatment feasible through anaerobic digestion. This anaerobic digestion produces useful energy in the form of biogas. However, the residual waste, coming out from the biogas plant, still has substantially high amount of organics, salts and colour, which do not meet the pollution norms.
There are some techniques /installations where incineration of spentwash is achieved with a different process which is similar to a recovery boiler used in paper industry to incinerate black liquor (process waste from pulp and paper). In this configuration, the fouling of tube bank is allowed to take place, which is cleaned subsequently by techniques like circulation
2

of stainless steel balls on a continuous basis through the boiler tube bank to induce vibrations and thereby cleaning the deposits of the alkali salts on the boiler tube bank.
In the recent times, some work has been done to blend the distillery spentwash with bagasse pith/ wheat bran and use a dryer to dry the mass to a level of 5% moisture. This can be used as a cattle feed or as a fuel.
It is also known to use coal and other agro wastes as fuel for the purposes of generation of steam.
Experiments were also conducted using agro waste fuels / spentwash with coal in fluidized bed combustion system. Various combinations of agro waste fuels / spent wash with various types of coal were studied. The studies have been directed towards firing the agro waste fuels / spent wash with suitable proportion of coal to avoid fouling / slagging problems. The drawback of this method is that the quantity of coal blending required and the resultant steam production with combination of coal observed to be very high than the captive requirement of the process plant resulting in increase in capital cost and operating cost.
Alternately, if the boiler is designed to meet the captive process steam requirement, the entire quantity of spent wash produced by the distillery is not incinerated and zero liquid discharge is not achieved.
DRAWBACKS OF THE PRIOR ART:
The prior art process for the usage of most of the agrowaste fuels and process wastes like spentwash has a low percentage of ash typically between 5-20%. However, in most of the cases, the ash has alkaline
3

components in the form of sodium, potassium and other salts ranging between 5-50%. These agro wastes fuels when used in fluid bed combustion or other, pose problems like bed agglomeration as well as fouling of heat transfer surfaces and slagging on combustor walls.
OBJECTS OF THIS INVENTION:
An object of this invention is to propose an improved method by which the agro waste / concentrated spentwash can be effectively incinerated completely avoiding fouling problems.
Another object of this invention is to propose such an improved method whereby the concentrated spentwash can be fully utilized for the purpose of generating energy and the waste can be disposed off without posing any pollution problem.
Another object of this invention is to propose such an improved method, which will provide added advantages like flexibility of operation and economics.
Another object of this invention is to propose a very minimal / no coal blending in order to produce steam to meet the requirement of the process plant.
SUMMARY OF INVENTION:
According to this invention there is provided an improved method using an apparatus for generating steam from wastes such as concentrated distillery waste.
4

According to another aspect of this invention there is provided an improved method of eliminating problems of bed agglomeration and fouling of tube banks during the combustion of concentrated spentwash with minimal / no coal blending.
In accordance with this invention there is provided an improved method for generation of steam required for the process plant by incinerating total waste produced in the plant.
DESCRIPTION OF THE DRAWINGS:
The invention will be described in detail with reference to a preferred embodiment. Reference to this embodiment does not limit the scope of the invention. In the accompanying drawing:
Figure 1 illustrates the proposed system wherein (3) is the normal known conventional Fluidized bed combustor with or without "inbed heat exchanger" (IBH) (2), extracting heat from the bed, capable of combusting concentrated spentwash. Spent wash is fed / injected into the combustor using a specially designed injection device (5) at appropriate elevation and the air is supplied with the assistance of blower / blowers (forced draft) FD fan (1) through steam fired air preheater (14). The fluidized bed (3) is operated at very high operating temperature. The products of combustion (flue gas) leaving the bed then enters a void (4) followed by void (6) where secondary / tertiary air is added through port (12) and (13) respectively for the combustion of volatiles. The voids (4) and (6) are enclosed with the help of either water walls / membrane panel / tube and tile arrangement / refractory, etc. The water walls provided in this zone helps to absorb heat from the flue gas and eventually the hot gas
5

is cooled substantially to avoid any fouling of further heat transfer surface (7) the evaporator section. The sufficiently cooled flue gas flows across the evaporator (7) to exchange heat and produce steam in the steam drum (10). The heat absorbing panel which surrounds the void (4) and (6) is also connected to steam drum (10). The exhaust flue gas from the evaporator then taken to any known dust collection equipment (8) like Bag filter / electro-static precipitator / cyclone separator, etc. After separating the particulate matter to sufficient level the gas is exited through an ID fan (9) into the atmosphere.
ADVANTAGES OF THE INVENTION:
1. Problems of bed agglomeration and fouling of tube banks are eliminated during the combustion of concentrated spentwash with very minimal or no coal blending.
2. The concentrated spentwash can be fully utilized for the purpose of generating energy and the waste can be disposed off without posing any pollution problem.
3. Flexibility and ease of operation coupled with techno economic viability.
While considerable emphasis has been placed herein on the specific structure of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly
6

understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

Dated this 7th day of April 2006

Mohan Dewan

Of R. K. Dewan & Co

Applicant's Patent Attorney

7