Ethanol continuous flow boiler

An improved boiler that allows distillation of ethanol from a continuous flow of a hydrous feedstock compound, which may be beer or other semi-solid substance. The internal compartment of the boiler is separated into different zones by a plurality of primary baffle plates and secondary baffle plates. The hydrous feedstock compound is heated as it passes from one zone to another zone and ethanol inside the hydrous feedstock compound vaporizes. The ethanol rich vapor is channeled through a collector column and then collected for further processing. The temperature of the hydrous feedstock compound is slightly different from one zone to another zone because of ethanol concentration changes as the hydrous feedstock compound moves from one zone to another. At the last zone, where most of ethanol is removed, the remaining hydrous feedstock compound is removed from the boiler.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to apparatuses for distillation. More particularly, the present invention relates to a boiler that distills ethanol from a continuous flow of feedstock.

2. Description of the Related Art

Ethanol is gaining wide popularity as a fuel, particularly when used as a component mixing with gasoline. Gasoline mixture may contain up to about 10 vol. % ethanol, without modifications to presently used automobile engines being required, thereby extending the volume of motor fuel availability by a like percentage. Ethanol has been produced for thousands of years around the world. Distilled spirits (higher concentrations of ethanol in water) is made from fermenting, boiling, and condensing beer or wine. Ethanol is completely miscible in water, allowing a homogenous solution of 0% to 100% ethanol to water mixture. Ethanol boils off at a lower temperature than water, allowing the ethanol to be concentrated through distillation. However, at a 96% ethanol to water mixture, the ethanol and water will boil at the same temperature (an azeotropic mixture). This 96% concentration is the knee on the curve that distillation cannot overcome when one works to remove all of the water in ethanol.

The primary source of the ethanol used in gasohol is derived primarily from the fermentation of mash, and usually from corn. Natural fermentation is able to produce an ethanol-water product mixture containing about 12-20 vol. % ethanol. This mixture may easily be concentrated by distillation to about 95% ethanol. Higher concentrations of ethanol, however, as required in a mixture of gasoline with ethanol, are obtained only by dehydration methods other than distillation due to the formation of an ethanol-water azeotrope at about the 95% ethanol concentration.

The ethanol producing process for small producers is generally in batch mode. It starts with a mixture of the fermentation of mash that enters in a boiler and then the mixture is heated to extract the ethanol. After boiling the mixture for a certain period, the remaining mixture is drained and removed from the boiler. After the boiler is emptied, a new batch of the mixture is fed into the boiler and the cycle repeats. This batch mode is time consuming since, for each cycle, it involves filling up and emptying the entire content of the boiler and consumes more energy since the boiler cools down during the replenishing of the mixture. It is also difficult for the batch mode to recover heat from spent mesh.

Thus, it is desirable to have a system that is energy efficient and can continuously distill ethanol, and it is to such a system the present invention is primarily directed.

SUMMARY OF THE INVENTION

The present invention enables the possibility of continuous distillation of ethanol from a continuous flow of feedstock. In one embodiment, there is provided an ethanol boiler with a substantially horizontal main body having a hollow interior thereof. The hollow interior has a top portion and bottom portion and first end and second end. The first end includes an inlet for admitting a flow of an ethanol-containing semi-liquid feedstock into the interior of the body, and the second end includes an outlet for the semi-liquid feedstock. The ethanol boiler also includes a plurality of baffle plates within the interior of the body between the first end and second end, at least one heating element for heating the semi-liquid feedstock while the feedstock passes from the inlet to the outlet, and at least one vent on the top portion of the body. The vent allows vaporous ethanol to exit from the interior of the body. Each baffle plate has at least one passage therethrough to allow passage of the semi-liquid feedstock from the inlet to the outlet.

In another embodiment there is provided a method for distilling ethanol from a hydrous feedstock compound using a continuous flow boiler with a plurality of heating zones. The method includes admitting the hydrous feedstock compound into the continuous flow boiler, heating the hydrous feedstock compound, collecting ethanol vapor resulted from heating the hydrous feedstock compound, moving the hydrous feedstock compound through the plurality of heating zones, and draining the hydrous feedstock compound from the continuous flow boiler.

Other objects, features, and advantages of the present invention will become apparent after review of the hereinafter set forth in Brief Description of the Drawings, Detailed Description of the Invention, and the Claims.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a process of production of ethanol. A hydrous feedstock compound containing ethanol, water, and potentially some impurities from the fermentation is fed into a boiler that is divided into different zones. The hydrous feedstock compound may be beer or other semi-solid substance. The hydrous feedstock compound, which is ethanol-containing semi-liquid feedstock, results from fermentation of corn or other suitable farm products and is fed into the boiler and heated as it moves from one zone to a next zone. Because of different boiling temperatures, ethanol boils first and vaporizes. The vapor containing ethanol is channeled through a separator column and collected for further dehydration. The boiler with multiple zones allows different temperature in each zone since the concentration of ethanol changes as the hydrous feedstock compound moves from one zone to another. The continuous flow boiler improves the efficiency of the process for distilling ethanol by improving the throughput and efficiency of batch processes, as is common in prior art distillers and boilers. However, some vertical columns can still be used in conjunction with or as part of the present inventive boiler.

FIG. 1illustrates a schematic of a multi-zone horizontal, hollow compound boiler100. The multi-zone compound boiler100includes preferably a cylindrical boiler shell102. The compound boiler100is manufactured from a metallic material, preferably a corrosion resistant material. The cylindrical boiler shell102is enclosed on both ends by two circular plates103,104, and thus forming an internal compartment (chamber). The internal compartment is divided into multiple zones through multiple primary baffle plates116and secondary baffle plates118. The primary baffle plates116and secondary baffle plates118are placed inside the internal compartment.FIG. 9illustrates a total of nine zones inside the compound boiler100; however, it is to be understood that the compound boiler100may have a different number of zones. Alternatively, the secondary baffle plates118may not be needed. The features of the secondary baffle plates118may be incorporated into the primary baffle plates116.

FIG. 2illustrates a schematic200for a primary baffle plate116. The primary baffle plate116is generally circular with a secant edge208, a liquid flow channel206, a floating solid channel202, passages204for support rods126(shown inFIG. 1), and one or more holes210for heating elements114(shown inFIG. 1). The secant edge208allows the top portion of the internal compartment to form a vapor flow channel128(shown inFIG. 1), which is shared by all zones, and thus permitting the vapor from each zone to move toward a separator column106(shown inFIG. 1). The separator column106acts like a vent to the boiler100collecting vapor exiting from the boiler100. Those skilled in the art will appreciate that multiple separator columns may be used with the boiler100.

FIG. 3illustrates a schematic300for a secondary baffle plate118. The secondary baffle plate118has a size that allows it to cover the liquid flow channel206when overlaid over the primary baffle plate116. The secondary baffle plate118has a passage302, which is approximately the same size as the passage204, for a support rod126.

The compound boiler100receives the hydrous feedstock compound through an inlet112connected to the circular plate104. The compound boiler100is equipped with a plurality of heating elements114. The heating elements114may be electrical heating rods; alternatively, the heating elements114may also be gas or hot liquid powered. The heating elements114go through the primary baffle plates116and heat the hydrous feedstock compound in each zone. The heating elements114may be removed from the assembly of the primary baffle plates116and the compound boiler100for maintenance, cleaning, and repair. The hydrous feedstock compound passes through different zones and is finally collected by an outlet120. The hydrous feedstock compound collected by the outlet120is channeled through a connection122to external facilities for further processing. The continuous nature of the boiler allows the hydrous feedstock compound coming out from the connection122can be used to preheat the liquid entering in the inlet112thereby gaining energy efficiency.

The compound boiler100is equipped with a liquid level controller110and an overfill level controller108. The level of the hydrous feedstock compound inside the compound boiler100is sensed by a liquid level controller110. When the level of the hydrous feedstock compound drops below the liquid level controller110, additional hydrous feedstock compound is pumped or fed into the compound boiler100. The overfill level controller108can sense the overflow condition. If an overflow condition is detected, the overfill level controller108sends a signal to stop the operation of the compound boiler100. The compound boiler100may also be equipped with an underfill level controller111for sensing the underfill condition. A prolong indication of low level by the underfill level controller111will shut down the operation of the compound boiler100, since it may be an indication of malfunction of the compound boiler100.

The compound boiler100is also equipped with a thermo-controller124. The thermo-controller124senses the temperature of the hydrous feedstock compound and controls the outlet120accordingly. Under a certain pressure condition, the majority of ethanol inside the hydrous feedstock compound would have vaporized at a given temperature. When the thermo-controller124detects at a preset temperature, the thermo-controller124sends signal to open the outlet and a quasi-ethanol free hydrous feedstock compound will flow out from the compound boiler100.

The internal compartment of the compound boiler100is divided into different zones by the primary baffle plates116and the secondary baffle plates118, each zone1-9being a boiling zone. The primary baffle plates116prevent significant hydrous feedstock compound exchange between boiling zones. Separated zones allow the hydrous feedstock compound to be boiled at different temperatures and ethanol concentrations. The primary baffle plates116and the secondary baffle plates118are held in position by the support rod126. It is understood that multiple support rods may also be used. The heating elements114extend through all the zones and heat hydrous feedstock compound in each boiling zone. Those skilled in the art will also appreciate that individual heating elements may be employed for each zone. The secondary baffle plates118placed in the lower portion of the internal compartment of the compound boiler100limit the exchange of significant amounts of hydrous feedstock compound and heat when the level of the hydrous feedstock compound in adjacent zones are equal or similar.

Though the compound boiler100is separated into different zones, the hydrous feedstock compound may flow from one zone to an adjacent zone through the liquid flow channel206. The sediments may also flow from one zone to another through the liquid flow channel206. Floating solids that may be present in the hydrous feedstock compound can move from one zone to another through the floating solids channel202. The floating solids channel202permits passage of the floating solids without significant passage of the hydrous feedstock compound or heat exchange between adjacent zones.

As the heating elements heat the hydrous feedstock compound in each zone, the ethanol inside the hydrous feedstock compound vaporizes. The ethanol rich vapor flows through the vapor flow channel128toward the separator column106. The vapor will be collected at different facility to further process the ethanol.

FIG. 4is a flow chart400for an ethanol distillation process according to the invention. Liquid containing ethanol (the hydrous feedstock compound) is sucked, pumped, or otherwise admitted into the boiler100through the inlet112, step402, until a high-level mark is reached, step404. The high level of the hydrous feedstock compound is sensed by the liquid level controller110. Once the boiler100is at its full capacity, the heating elements114are energized, step406. Boiling of the hydrous feedstock compound occurs, and ethanol vapor passes from each zone through the vapor flow channel128exits the boiler110through the separator column106, step408. Boiling continues until a preset temperature is sensed by the thermo-controller124, step410. The preset temperature approaches the boiling point of water at the pressure present in the boiler100. When the preset temperature is reached, it is an indication that the ethanol is mostly vaporized, and a portion of hydrous feedstock compound can be removed from the boiler100through the outlet120, step412. The hydrous feedstock compound removed from the boiler100may be carrying out the spent liquid, floating solids, and sediment. The removal of the hydrous feedstock compound stops when the thermo-controller124senses a significant portion of the hydrous feedstock compound has been removed and additional hydrous feedstock compound will be introduced into the boiler100. The thermo-controller124may be able to sense the removal of the hydrous feedstock compound because when cooler liquid from the adjacent zone flow across the thermo-controller124, the thermo-controller124's temperature will decrease significantly. Alternatively, a given quantity of liquid may be pumped from the boiler100at a given periodicity to match a given heat input via the heating element.

During the ethanol distillation process, the liquid and sediment in the hydrous feedstock compound pass through the liquid flow channel206and liquid and floating solids pass through the floating solids channel202from one zone to an adjacent zone because a difference in the liquid levels in adjacent zones causes a differential pressure. The liquid flow continues between the zones until the zone with the liquid level controller110senses a low hydrous feedstock compound level. Additional hydrous feedstock compound is sucked or pumped into the boiler100through the inlet112to raise the liquid level. If the liquid level is not controlled, the overfill level controller108or the underfili level controller111shuts down the operation of the boiler100. Ethanol in the hydrous feedstock compound vaporizes and cools down the hydrous feedstock compound inside the boiler100. An equilibrium is established where different zones boil the ethanol at different temperatures due to the different concentrations of ethanol. The different temperatures and concentrations are maintained due to the primary baffle plates116and the secondary baffle plates118. The level of the hydrous feedstock compound is maintained by the liquid level controller110and ethanol concentrations are controlled by sensing the temperature via the thermo-controller124and pumping the spent liquid out of the outlet120. The heating elements114boil the ethanol and maintain the temperature.

In operation, an ethanol rich, semi-liquid feedstock is fed into the boiler100as shown inFIG. 5, where the feedstock is at a room temperature of 70° F. Once inside the boiler100, the semi-liquid feedstock is heated up as shown inFIG. 6, where the feedstock is shown with 212° F., enabling the ethanol inside the semi-liquid feedstock to vaporize. The vapor is collected by the separator column for further processing. After the semi-liquid feedstock reaches a predefined temperature detected by the thermo-controller124, the connection122to an external tank is open and the semi-liquid feedstock flows out from the collector120as shown inFIG. 7. The feedstock that flows out from the boiler100can be used to pre-heat the replenishment feedstock that will be entering into the boiler100. The level of the semi-liquid feedstock in each zone drops as the feedstock flows from one zone to another toward the outlet120. When the level of the feedstock drops to a certain level, the inlet112is open and the replacement feedstock of lower temperature flows in as shown inFIG. 8. The newly arrived feedstock is mixed with the remaining feedstock, thus raising the temperature of new mixture. The newly arrived feedstock enters into the first zone, raises its level, and forces the feedstock in the first zone to flow to the adjacent zone. As the feedstock flows from one zone to another, the level tends to adjust to the same level as shown inFIG. 9and the distillation process described above repeats itself.

The boiler100can also support a continuous distillation process. After the boiler100is filled with the feedstock as shown inFIGS. 5 and 6, when the temperature reaches a predefined level, the outlet122is open and the feedstock flows out from the boiler100. As the outlet122is open, the inlet112is also open to allow new feedstock to flow in. As the cooler feedstock flows in from the inlet112and hotter feedstock flows out from the outlet122, the flow of the feedstock inside the boiler100is depicted inFIG. 8. The semi-liquid feedstock moves continuously from one zone to an adjacent zone. As the ethanol vaporizes, the concentration of the semi-liquid feedstock changes slightly, thus the temperature also increases slightly. With a the addition of heat, additional ethanol still inside the semi-liquid feedstock vaporizes, thus producing additional vaporized ethanol. This lowers the ethanol concentration and raises the boiling temperature of the feedstock. When the semi-liquid feedstock reaches a last zone, it will be heated up to a predetermined temperature. At the predetermined temperature, most of ethanol inside the semi-liquid feedstock would have been vaporized, and the remaining semi-liquid feedstock can then be removed from the boiler100. As the remaining semi-liquid feedstock is removed from the boiler100, new semi-liquid feedstock is added into the boiler100in a continuous fashion. An equilibrium is established as depicted inFIG. 9.

The boiler100is in essence a continuous flow boiler and continuously distills ethanol from a flow of semi-liquid feedstock. New semi-liquid feedstock is added almost constantly whenever the level of the semi-liquid feedstock inside the boiler drops below a predetermined level. The semi-liquid feedstock at the very last zone is also removed continuously after a predetermined temperature is achieved. By adding small amount of semi-liquid feedstock each time, the temperature of the semi-liquid feedstock inside the boiler can be maintained at a high temperature, making vaporization a continuous process, thus maximizing the production capacity and efficiency of the boiler.

Although preferred embodiments of the invention have been disclosed in the foregoing specification, it is understood by those skilled in the art that many modifications and other embodiments of the invention will come to mind to which the invention pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. Moreover, although specific terms are employed herein, they are used in a generic and descriptive sense only, and not for the purposes of limiting the described invention.