WO2009025542A1

WO2009025542A1 - Improved process of refining crude vegetable oil and animal fats for biodiesel feedstock

Info

Publication number: WO2009025542A1
Application number: PCT/MY2008/000014
Authority: WO
Inventors: Ruslee Hussain
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-02-26
Filing date: 2008-02-26
Publication date: 2009-02-26
Anticipated expiration: 2010-08-26

Abstract

The invention discloses a method and a process to cost effectively manufacture biodiesel feedstock from crude vegetable oils and or animal fats (represented by the dotted arrows) via continuous process by attaching a specially designed modified and simplified oil refinery as in Figure 1, wherein the refined oil from the bottom of distillation column (14) is used as the thermal oil(represented by the solid arrows) in the fatty acid fired thermopack heater(16) being fueled by the waste FFA from pipe(25) generated from condensing the vaporised FFA from pipe(21) into condenser(22) which lead into flash drum(23) which is equipped with heating coil heated by the refined oil from the refining process in the thermopack heating coil.

Description

IMPROVED PROCESS OF REFINESfG CRUDE VEGETABLE OIL AND ANIMAL FATS FOR

BIODIESEL FEEDSTOCK

Technical Field

[1] The present invention relates generally to the refining of crude vegetable oil or animal fats for biodiesel feedstock for a common and popular and generally economical biodiesel transesterification process, In particular, this invention relates to a method for the economical process of refining crude vegetable oil or animal fats via a modified continuous known chemical refining in combination with a modified continuous known physical refining by utilising the free fatty acid(FFA) byproduct as a clean and renewable fuel for the thermopack heater and the refined oil from the invented refining process as the heat transfer oil directly in the thermopack heater heating coils and heating lines. The invention uses only a FFA fired thermopack heater without the need for any steam boiler for the total heating requirement of the refining process. The use of petroleum based fuel and petroleum based heat transfer oil is totally obviated in the refining process. The invention provides an energy efficient, lower capital cost, space saving, lower operation cost and environmentally safe refining process and thus is an improvement over prior crude vegetable oil or animal fats refining method.

Background Art

[2] A typical vegetable or animal fats refinery uses petroleum fuel as fuel in the steam boilers and thermopack heaters. Petroleum based fuel like diesel and fuel oil are costly and pollute the environment. Generally for a physical refining process a steam boiler must be employed as life steam is needed in the steam stripping process and steam ejector for producing vacuum pressure apart from supplying the processing heat requirements. Thermopack heaters are used at the pre-stripping and deoderizing column to supply the necessary high temperature of about 275 Deg. Celcius for steam stripping distillation process. The use of a steam boiler is a high capital investment and operational cost and requires the employment of a certified boiler chargeman by law of almost all countries. A steam boiler requires the feed water to be treated and thus requires a water treatment facility and the use of chemicals to treat the water. The installation of a steam ejector is also another high captital cost which uses quite a substantial amount of steam to operate. Hence, a fuel cost for a typical vegetable/fats refinery can amount to as high as 50 percent of the total operational cost of the refinery.

[3] Vegetable oil/animal fat is one of the most important primary foods and therefore requires maximum quality for safe human consumption. The quality of the final product depends on the refining method and the nature of the raw oil. A typical r efinery for food production requires the oil to be degummed, deacidified, bleached and deoderized. However, for the production of refined oil as blodiesel feedstock, bleaching and deoderizing process can be omitted as the final product is classified as biofuel and not as food.

[4] Two common known processes have been used in refining edible oils and fats; the chemical refining and physical refining. The decision as to which process is to be used depends on the types and qualities of crude oil to be processed. Chemical refining method is the lesser capital cost compared to physical refining, where the free fatty acids of the crude oils are neutralized with caustic soda. The resulting sodium soaps or soapstocks are separated by using centrifugal separators. The neutral oils are subsequently bleached and deoderized. In physical refining, the free fatty acids are removed by distillation in one stage during deoderizing. A fundamental criteria for using this method is that the crude oils should be degummed as effectively as possible. However, this method does not produced soapstocks unlike the chemical refining method which requires another costly soapstock splitting process. Disclosure of Invention

Technical Problem

[5] The major limitation associated with a conventional vegetable oil/animal fats physical refinery is that the overall production facility requires a massive investment which comprises of peroleum fuel fired steam boilers, boiler feed water treatment plant, steam ejectors, petroleum fuel fired thermopack heaters, food grade stainless steel degumming facility, food grade stainless steel deacidifying facility, food grade stainless steel bleaching facility, food grade stainless steel deoderizing facility, food grade stainless steel heat exchangers and food grade stainless steel vacuum dryers.

[6] As the number of equipments used in a typical refinery is substantial, a very large amount of electrical energy is needed to power all the equipments stated above.

[7] A typical refinery uses large amount of water for steam generation and a larger water treatment plant is needed to accompany it. As large amount of water is used, the chances of polluting rivers and waterways always happened due to effluent water treatment shutdown and failures. [8] A typical refinery uses large amount of petroleum based fuel for the steam boilers and thermopack heaters. The burning of the fuel will contribute to polluting the environment as large amount of pollutants such as sulfur, NOx , CO and CO2 will be released to the environment.

[9] A typical refinery uses mineral based thermal oil or mineral based food grade thermal oil or mineral white oil or mineral based synthetic oil. These thermal oils are regarded as high temperature and high performance and are thus very costly. These thermal oils needs to be replenished and replaced from time to time as the quality and properties will degrade over a short period of time as the thermal oil is subjected to an extreme temperature of up to 350 Deg. Celcius and being exposed to air in the expansion tank of the thermopack system in certain cases. Replenishing the thermal oil requiring the plant to be shutdown and labor to carry out the job. This will also contribute to the running cost of the refinery.

[10] The crude vegetable oils/animal fats must be degummed effectively or completely for a biodiesel feedstock. The use of only physical refining method will necessitates the use of bleaching earth, pressure leaf filters or Magara filters to entrap the gums. The spent earth generated will contribute to some oil loss and will pose another problem and cost for disposal.

[11] The crude vegetable oils/animal fats must be deacidified effectively or completely for a biodiesel feedstock. For instance, crude jatropha oil can have an FFA content up to 10 % which can contribute to a large amount of soapstock being produced if the method selected is the chemical refining method alone. The soapstock will then need to be treated using soapstock splitting process to recover the FFA, another costly treatment as strong acids such as hydrochloric acid HCL and or sulfuric acids H2SO4 are normally used which requires the use of expensive extremely durable stainless steel tanks. Soaps of less attractive value will be produced in quite a large amount and hence will pose a problem to manage the storage, handling and sales of it. On top of that, oil loss will be very substantial.

Technical Solution

[12] The goal of the invention is to produce large amount of refined vegetable oil/animal fats for biodiesel feedstock and not for food production. As such the invention is avoiding the use of the extremely expensive kind of steel used in the refinery plant that is food grade stainless steel 316. The invention uses mostly mild steel and in certain areas stainless steel 304L which is much cheaper and sufficient enough to comply with the stringent safety and design requirement of the invention. [13] A smaller number of energy efficient equipments is used in the invention compared to the traditional method of physical refining. An efficient heat transfer method of cascading the heat using processing tanks heating jackets and heating coils where the heat is directly in contact with the process oil.

[14] The object of the invention is to avoid the use of any steam or steam boilers. As such, no large amount of water is required in the invention and water used in the invented method is recycled. ISb water treament plant is needed and the chances of polluting rivers and waterways is completely eliminated.

[15] Another object of the invention is to use the by-product from the distillation column called free fatty acid FFA to fuel the thermopack heater. This FFA is cleaner and renewable compared to any fossil fuel. The FFA distilled from the process has a comparable heating value and is more than enough to completely supply all the fuel needed by the thermo-pack heater. The excess FFA can be packed and sold as a renewable and cleaner boiler fuel or as oleo-chemical feedstock.

[16] Still yet another object of the invention is to used the processed oil as the thermal oil which avoided the use of any mineral based thermal oil or the need to purchase and replenish the thermal oil. Nb schedule shutdown is needed compared to the conventional method and this will contibute to a substantial cost saving. By directly heating the oil to be processed in the thermopack heater is the novel process to achieve a more energy efficient heat transfer. The process oil temperature can be achieved in a shorter period of time compared to the traditional heating a separate thermal oil first to a higher temperature than the process oil as some heat transfer loss occured in the commonly used plate heat exchangers. About 30 Deg. Celcius to 70 Deg. Celcius higher thermal oil operating temperature has to be used in the conventional thermopack heaters which translated to a higher energy requirement thus higher fuel cost.

[17] In order to minimize oil loss and achieve a desirable product cost effectively, a simplified and modified combination of the known processes; chemical refining and physical refining is used in the invention.

Advantageous Effects

[18] The invented refining process and method can be called a green refinery as the use of petroleum fuel is avoided completely.

[19] Less costly construction material such as mild steel pipes and plates are used extensively in the refinery process plant.

[20] The use of a greener and renewable fuel from the by-product of the process can reduce operation cost.

[21] Nb petroleum fuel needs to be purchased or transported to the refinery.

[22] ]Sb costly high temperature or high performance petroleum based heat transfer oil needs to be purchased, replenished or replaced.

[23] The refined oil acting as the thermal oil fluid is not subjected to contacts with air as the heating pipeline circuit is under vacuum. Hence there is no deterioration of the refined oil. Moreover the top temperature of 265 Deg. C is much lower than the traditional thermal oil system of about 320 Deg. C.

[24] Nb costly shutdown or maintenance needs to be carried out as opposed to the traditional method in replenishing or replacing the thermal oil. Shutdown due to this can be equally costly and unsafed as the heated section needs to be cooled down adequately before the replenishing job can be carried out.

[25] The invented process and method is more energy efficient in that it does not require shutdown as mentioned above which will require a heating start-up to heat the distillation section as heating start-ups consume large amount of fuel.

[26] The refining process does not require the use of any steam boiler. Less or no polluted water is generated.

[27] The refining process does not require the use of any steam ejector for vacuum requirement. Hence less energy requirement.

[28] The refining process does not generate soapstock by-product/waste.

[29] Nb water treatment plant is needed as the water used is recycled.

[30] A continuous 24/7 and 365 days per year running refinery is possible with the invented process and method.

Description of Drawings

[31] Figure 1 is the invented refining process flow schematic design.

[32] Figure 2 is the 2D design(front elevation) of the invented 50 Metric Tonne per day crude vegetable oils/animal fats refining plant.

[33] Figure 3 is the isometric view of the plant showing the small foot-print needed(6m x 24m or 20ft x 80ft) for a 50 Metric Tonne per day capacity.

[34] The following detail description is given by way of illustration only and therefore should not be construed to limit the scope and spirit of the present invention.

[35] This invention is characterized by the fact that the process flow design as depicted in Figure 1 is carried out as follows; About 1 Metric Tonne of refined oil is pumped into the bottom of distillation column(14) from tank(20) using the thermopack pump(15) and about 200 kg of preheated FFA is placed in the FFA flash drum(23). Then circulation is carried out by opening all the necessary valves in the process flow design pipelines (represented by the solid arrows). The vacuum pump(24) and (29) are then be started to remove air in the thermal heating pipelines with a setting of about 5mm to 10mm Hg. After air has been completely removed in the heating circuit pipelines as indicated by a constant pump pressure of about 3 bar, the thermopack is fired using the preheated FFA from the FFA flash drum(23). The refined oil which act as the thermal heating oil is quickly being heated-up by the thermopack heater to the required distillation temperature of around 270 Deg. C. Tank(l) with a capacity of 50 curie meter and equipped with a 30 square meter of hearting surface heating coils can heat-up a 2 metric ton per hour flow rate of crude oil from 30 Deg. C up to 130 Deg. C while flowing from the top to the bottom of the tank while being agjatated by the tank agitator of speed of about 50 rpm. Once the crude vegetable oil/animal fats has reached a process temperature of about 130 Deg. C, a variable-speed pump(4) is started to deliver about 2 MT/hour flow rate. Industrial grade phosphoric acid H3PO4 of about 85% purity is dosed from chute(3) via a metering pump(not shown) at about 0.01 % to 0.1% weight depending on the quality of the crude vegetable/animal fats. The mixture is further agitated by the high speed agitator of speed of 2800 rpm at the bottom of the acid mixing tank(5) equipped with heating coils to maintain or regulate the required processing temperature. A small amount of mild liquid caustic soda is dosed from chute(6) via a metering pump(not shown) to neutralise the acids in the process crude oil. The mixtures then enters mild caustic mixing tank(7) to be further agitated by the bottom agitator of speed 2800 rpm. Gums, phosphatides and sludges are continuouly removed from the mixture in centrifugal separator(8) into a container(not shown). Meanwhile the degummed oil travels to the top of the separator where it meets chute(9) where a small of amount of hot water is dosed(if necessary depending on the quality of the crude oil) via a metering pτimp(not shown) to hydrate any traces of phosphatides remaining in the crude oil. The degummed oil and hot water mixtures then travel to the hot water mixing tank(7) to be agitated by the bottom mixer to 2800 rpm. The required process temperature is achieved by controlling the tank heating coils temperature. The agitated mixtures then travel to a centrifugal purifier(ll) where the degummed oil is separated from the water, hydrated phosphatides and sludge. The separated impurities can be recycled(recycle line not shown) to the separator(8) in order to further minimize oil loss. Most of the other impurities like sludge can be collected from the bottom of the purifier into a container(not shown). [36] The slightly less than 2 MT/hour crude degummed oil then enters the bottom of the two-stages dearation column(12) with a temperature in the region of 110 Deg. C to 150 Deg. C. Any remaining traces of water vaporises to the top of the dearation column into pipe(26) and then into a water cooled(cooling water pipings and cooling tower not shown) condenser(27) into the distilled water flash drum(28). Here the distilled water is collected and necessarily heated by the heating coils to the required hot water temperature needed by the centrifugal purifier(l 1) via line(30). The variable-speed pump(13) then pumps the oil to the top of the first stage of the dearation column(12) to undergo further removal of traces of water. The oil collected in the first stage tray will be heated by the heating jacket of the first stage to a temperature closed to 265 Deg. C as the oil in the jacket comes directly from the thermopack heater. The heated processed oil then enters the first stage of the FFA distillation column(14) where FFA will be vaporised and pulled by the vacuum pump(24) into the FFA flash drum(23) via pipe(21) and condenser(22). The degummed and deacidified oil then drops into the second stage of the FFA distillation column and then later to the third stage of the distillation column. Once the degummed and deacidified reached the bottom of the distillation column, it has been completely refined as almost all the FFA has been vaporised. [37] The refined oil at the bottom of the distillation column(14) now enters the thermopack heater(16) via a variable-speed pump(15) and functions as a thermal oil fluid to supply all the necessary heating process requirements of the refinery. The thermopack heater temperature contoller is used to regulate and control the highest temperature requirement of the process. The heated processed oil then travels to the heating jacket of the first stage dearation column(12) and then into the first stage heating jacket of the FFA distillation column(14), then to the second stage heating jacket of the distillation column(14), then to the third stage heating jacket of the distillation column(14), then into the heating jacket of the bottom of the distillation column(14). Once the heating jacket of the bottom of the distillation column is full, the refined heating oil will then travel to the second stage heating jacket of the dearation coulmn(12) before entering the bottom jacket of the dearation column(12). The flow rate and pump pressure of the refined heating oil is supplied and controlled by the variable-speed thermopack heater pump(15) which then now pumps the refined heating oil out of the heating jacket of the bottom of dearation column(12) into pipeline(18) to heat tank(l). Cooling water exchanger(31) is used to regulate the refined heating oil temperature to supply the necessary heat needed for the crude oil tank(l). Meanwhile cooling exchanger(32) in pipeline(19) is used to lower or cooled down the refined oil before entering the refined vegetable oil/fats tank(20) as a finish product that is suitable as a blodiesel feedstock.

Claims

[1] An improved method and process for the commercial production of biodiesel feedstock from crude vegetable oil and animal fats, which comprises;

(a) The method and process design as in (Figure 1) wherein the refined oil from the bottom of distillation column (14) is used as the thermal oil in the fatty acid fired thermopack heater(16) being fueled by the waste FFA from pipe(25) generated from condensing the vaporised FFA from pipe(21) into condenser(22) which lead into flash drum(23) equipped with heating coil.

(b) Refined oil from the crude refining process is used in all the heating coils; crude vegetable oil tank(l), acid mixing tank(5), alkaline neutralization tank(7), hot water mixing tank(lθ), the heating jackets of dearation column(12), the heating jackets of FFA stripping/distillation column(14), FFA flash drum(23) and water flash drum(23).

(c) The use of the fatty acid fired thermopack heater(16) heat temperature controller in combination with cooling water exchanger (31), cooling water exchanger(32), variable speed feed pump(4), varible speed dearation column pump(13) and variable speed thermopack pump(15) to regulate the process flow rate and temperature of the refinery.

[2] A process as claimed in claim 1 wherein the refined oil by the oil refinery is used as the heating heat transfer oil in the thermo-pack heater unit, heating coils, heating jackets, heating exchangers and heating pipelines.

[3] A process as claimed in claim 1 wherein the waste/by-product FFA obtained from the FFA stripping/distillation column is used to fuel the thermo-pack heater.

[4] A process as claimed in claim 1 wherein the crude vegetable oil or animal fats is selected from crude palm oil, crude jatropha oil, crude coconut oil, crude mustard oil, crude soybean oil, crude linseed oil, crude cottonseed oil, crude rapeseed oil, crude sunflower oil, crude safflower oil, crude tung oil, crude castor oil, crude olives oil, crude pecan oil, crude avocado oil, crude jojoba oil, crude cocoa oil, crude macademia oil, crude brazil nut oil, beef tallow, sheep and goat tallow, sperm whale oil, fish oil, pork lard and mixtures thereof.