Method and system for generating auxiliary power in an oil palm mill

Abstract

A method and a system for generating auxiliary power in an oil palm mill, where exit steam (50) from a sterilizer (30a, 30b, 30c, 30d) is supplied to a secondary steam turbine (T2) to produce the auxiliary power. Steam (40) flows freely into the sterilizer, flows freely within the sterilizer, and flows freely out of the sterilizer to power the secondary steam turbine (T2).

Description

[0001] METHOD AND SYSTEM FOR GENERATING AUXILIARY POWER IN AN OIL PALM MILL

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method and system for generating auxiliary electrical power in an oil palm mill, and particularly to a method and system that utilizes steam for generating auxiliary power.

[0004] BACKGROUND ART

[0005] Due to the remote location of most palm oil mills and / or costly electricity tariffs of the national grid, it has traditionally been a practice for oil palm mill to be self-sufficient with regard to their energy needs. For this, the traditional oil palm mill is equipped with a boiler that powers a steam turbine for generating electricity. Steam from the boiler or exhaust steam from the turbine is then relayed to a Back Pressure Receiver that regulates the steam to the sterilizers for sterilizing fresh fruit bunches (FFB). Steam to the sterilizers any also be delivered directly from the boiler or turbine.

[0006] The sterilization process results in a huge amount of steam that is simply released to the atmosphere and / or ends up as condensate. The condensate forms a significant part of the palm oil mill effluent (POME), generated from the milling process, which requires extensive and costly treatment. The treatment includes ponding systems that require a significant amount of space and include both aerobic and anaerobic biological processes. The anaerobic treatment liberates methane, a greenhouse gas, into the surrounding atmosphere, which requires methane capture facility that is expensive. Since a sizable amount of the POME originates from the waste steam from the sterilizers, an apparent method of reducing POME is to reduce the waste steam condensate from the sterilizers. With regard to environment concerns it is expedient for present-day oil palm mills to reduce steam condensate in the sterilizers and to have means to better manage steam utilization in the mill, thereby reducing the amount of POME generated.

[0007] With regard to the issue of reducing POME, and referring to Figure 1 herein, in Malaysian patent application no. PI 2023003127, Yeong King Hui discloses a method and associated sterilizer 1 for dynamically sterilizing oil palm FFB 2 in order to minimize POME generation. The sterilizer 1 is configured for receiving steam 3 at substantial flowrate and quantity, for a time sufficient for the fruitlets to detach from the bunches, and to allow the steam 3 to freely flow within the sterilizer 1, and for the steam 3 to freely leave the sterilizer 1 as exit steam 4. This results in a decrease in waste steam condensate in the sterilizer and thereby a reduction in the amount of POME. PI 2023003127 therefore addresses one part of the problem, i.e., reducing steam condensate in the sterilizers.

[0008] There is a need in the industiy to address the other part of the problem, i.e., better management of steam in an oil palm mill

[0009] SUMMARY OF THE INVENTION

[0010] The invention disclosed herein addresses the problem of better utilization of steam in an oil palm mill especially waste steam, which otherwise is just vented to the atmosphere and / or reduced to condensate which increases palm oil mill effluent (POME) since waste steam condensate constitutes a significant part of POME.

[0011] It is therefore an objective of the present invention to provide a simple, environmentally - friendly and cost-effective method for utilizing steam and thereby reducing POME and in effect reducing the overall carbon footprint of an oil palm mill.

[0012] To this end, it is an objective of the present invention to provide a method of generating auxiliary power in an oil palm mill, where the mill has a boiler, a typical primary steam turbine for generating electrical power, and a Back Pressure Receiver for regulating steam, wherein the method comprises the steps of:

[0013] - heating at least one FEB sterilizer with steam, wherein the steam flows freely into the sterilizer, flows freely within the sterilizer, and flows freely out of the sterilizer as exit steam; and

[0014] - channelling the exit steam to a secondary steam turbine to produce auxiliary power. the secondary steam turbine produces turbine exhaust steam and turbine condensate as waste. The secondary turbine is specially designed to utilise turbine exhaust steam and turbine waste condensate.

[0015] According to this method, the steam flows freely into the sterilizer, flows freely within the sterilizer while directly heating the FEB, and flows freely out of the sterilizer unimpeded as exit steam, lire steam has substantial flowrate and quantity to achieve the necessary sterilization of the FFB. This results in reduced waste steam condensate compared to conventional methods, thus directly reducing the amount of POME generated, since the residence time of a given amount of steam within the sterilizer is dramatically reduced.

[0016] It is a further objective of the method of the present invention that the power from the primary steam turbine may be channelled to an external power grid for non-oil palm mill use while the auxiliary power from the secondary steam turbine is used internally for the electrical needs of the oil palm mill itself.

[0017] It is a further objective of the method of the present invention that the power from the primary steam turbine may be channelled to an independent power user while the auxiliary power from the secondary steam turbine is used internally for the oil palm mill

[0018] It is a further objective of the present invention that the auxiliary power from the secondary steam turbine may be channelled to an external grid for non-oil palm mill use. It is a further objective of the method of the present invention that the auxiliary power from the secondary steam turbine may be channelled to an independent power user.

[0019] It is a further objective of the method of the present invention that the steam from the boiler may be channelled directly to the secondary steam turbine.

[0020] It is a further objective of the method of the present invention that the steam from the primaiy steam turbine may be channelled to the secondary steam turbine, particularly if the exit steam from the sterilizer is insufficient for the secondary steam turbine.

[0021] It is a further objective of the method of the present invention that the steam from the Back Pressure Receiver may be channelled to the secondary steam turbine, particularly if the exit steam from the sterilizer is insufficient for the secondary steam turbine.

[0022] It is a further objective of the method of the present invention that the turbine exhaust steam from the secondary steam turbine may be recycled back to the Back Pressure Receiver, particularly for utilization as re-heating energy in the oil palm mill.

[0023] It is a further objective of the method of the present invention that the turbine condensate from the secondary steam turbine may be recycled back to the Back Pressure Receiver.

[0024] It is a further objective of the method of the present invention that turbine condensate from the secondary steam turbine may be recycled back to the mill for heating use.

[0025] It is a further objective of the method of the present invention that the exit steam from the sterilizer may be relayed to a second Back Pressure Receiver prior to delivery to the secondary steam turbine.

[0026] It is a further objective of the method of the present invention that the turbine exhaust steam from the secondary steam turbine may be utilized for steam drying of decanter cake generated in the milling process. It is a further objective of the method of the present invention that the turbine exhaust steam from the secondary steam turbine may be utilized for steam drying of heavyphase liquids generated in the milling process.

[0027] It is a further objective of the method of the present invention that the turbine exhaust steam from the secondary steam turbine may be used for drying POME.

[0028] It is yet a further objective of the present invention to provide a system for generating auxiliary power in an oil palm mil I where the mill has a boiler, a typical primary steam turbine for generating electrical power, and a Back Pressure Receiver for regulating steam, wherein the system comprises at least one sterilizer that is configured for free inflow of steam, free internal flow of steam, and free outflow of steam as exit steam, and a secondary steam turbine to produce auxiliary power. Ibis system is characterized in that the secondary steam turbine is in fluid communication with the exit steam from the at least one sterilizer to produce the auxiliary power.

[0029] It is a further objective of the system of the present invention that the secondary steam turbine may be in fluid communication with the boiler, particularly if the exit steam from the sterilizer is insufficient for the secondary steam turbine.

[0030] It is a further objective of the system of the present invention that the secondary steam turbine may be in fluid communication with the Back Pressure Receiver, particularly if the exit steam from the sterilizer is insufficient for the secondary steam turbine.

[0031] It is a further objective of the system of the present invention that the secondary steam turbine may be in fluid communication with the primary steam turbine, particularly if the exit steam from the sterilizer is insufficient for the secondary steam turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 illustrates the Prior Art dynamic sterilizer as disclosed in Malaysian patent application no. PI 2023003127.

[0033] Figure 2 schematically illustrates the system for generating auxiliary power of the present invention.

[0034] Figure 3 schematically illustrates the system for generating auxiliary power of the present invention according to another preferred embodiment.

[0035] In describing the preferred embodiments of the present invention, which is illustrated in Figures 2, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific terms so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.

[0036] DESCRIPTION OF PREFERRED EMBODIMENTS

[0037] Referring to Figure2, there is shown a preferred embodiment of the present invention where a method of generating auxiliary power in an oil palm mill is disclosed. According to the method, steam from boiler 10, or any other primary steam source, is supplied to a primary steam turbine T1 for normal power generation for the mill. The steam, now exiting the primary steam turbine T1 , is relayed to a Back Pressure Receiver 20. The steam from the Back Pressure Receiver 20 is then relayed to at least one sterilizer (30a, 30b, 30c, 30d) which is configured for dynamic sterilization of FFB, where the steam 40 flows freely into the sterilizer, flows freely within foe sterilizer, and flows freely out of the sterilizer as exit steam 50. In the conventional process, the exit steam 50 is simply shunted to the atmosphere as waste steam and / or becomes waste condensate that ultimately ends up as POME. In the present invention, since the steam 40 is unimpeded by the sterilizer (30a, 30b, 30c, 30d) without any obstruction to confine the steam within the sterilizer, the exit steam 50 has a high flowrate and quantity. This exit steam 50 is then relayed to a secondary steam turbine T2 to produce auxiliary electrical power, fulfilling the purpose of the present invention. A plurality of sterilizer (30a, 30b, 30c, 30d) is expediently used so that there is sufficient and constant supply of exit steam 50 to the secondary steam turbine T2 in the event there are sterilizers that are in the process of loading, unlading, maintenance, etc. There may, naturally, be more than one secondary steam turbine though one is sufficient.

[0038] In another preferred embodiment of the present invention, instead of tying the power from the primary steam turbine T1 for mill use, it may be exported to an external power grid, such as the national power grid, for non-oil palm mill use. In this arrangement, the mill is powered by the auxiliary power from the secondary steam turbine T2. The power from primary steam turbine T1 may also be supplied to third-party power users, such as an independent pelletizing plant. ,

[0039] In another preferred embodiment of the present invention, the auxiliary power from the secondary steam turbine T2 may be exported to an external grid for non-oil palm mill use. Here too, the power from secondary steam turbine T2 may also be supplied to third-party power users.

[0040] In the event that there is insufficient exit steam 50 for the secondary steam turbine T2, steam may be directly supplied from the Back Pressure Receiver 20 or primary steam turbine T1 to compensate for the insufficiency.

[0041] In another preferred embodiment of the present invention, the turbine exhaust steam 60 from the secondary steam turbine T2 is used in various ways. For instance, it may be channelled to the Back Pressure Receiver 20 for various uses including utilization as re-heating energy in the oil palm mill. Or it is used for steam drying of decanter cake, heavy-phase liquids, POME, etc.

[0042] In yet another preferred embodiment of the present invention, a system for generating auxiliary power in an oil palm mill in provided where the mill has a boiler 10, or any other primary steam source, a typical primary steam turbine T1 tbr generating electrical power, and a Back Pressure Receiver 26 for regulating steam. The system comprises at least one sterilizer (30a, 30b, 30c, 30d), based on the concept of dynamic sterilization, that is configured tbr free inflow of steam 40, free internal flow of the steam, and free outflow of the steam as exit steam 50. For producing the auxiliary power, the exit steam 50 from the sterilizer (30a, 30b, 30c, 30d) is fluidly connected to a secondary steam turbine T2. Ideally the exit steam 50 is relayed directly to the secondary steam turbine T2. It is also withing the scope of this invention that the exit steam 50 may be indirectly relayed to the secondary steam turbine T2, for example, via a second Back Pressure Receiver 70 as illustrated in Figure 3.

[0043] The secondaiy steam turbine T2 produces sufficient electricity to fully run the mill. The secondary steam turbine T2 may be connected to the outer grid for external use, the auxiliary electricity exported for an additional source of revenue. For situations where there may be insufficient supply of exit steam 50 from the sterilizer (30a, 30b, 30c, 30d), the secondary steam turbine T2 may be supplied with steam directly from any other source, such as the boiler 10, the Back Pressure Receiver 20 or the primary steam turbine T1.

[0044] The modes or embodiments of the invention described herein are only meant to facilitate understanding of the invention and should not be construed as limiting the invention to those modes or embodiments only, T hose skilled in the art will appreciate that the modes or embodiments of the invention described herein are susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications which fall within the scope of the inventive concept hereof. INDUSTRIAL APPLICABILITY

[0045] The present invention finds ready industrial applicability in the palm oil industry as it is a method of managing steam, especially waste steam, in an oil palm mill. Particularly, the present invention provides a means for generating electricity that can be utilized for uses other than the mill itself by exporting the electricity to the general power grid.

Claims

CLAIMS1. A method of generating auxiliary power in an oil palm mill having a boiler (10), a primary steam turbine (T1) for power generation, and a Back pressure Receiver (20), comprising the steps of:(a) heating at least one sterilizer (30a, 30b, 30c, 30d) with steam (40), wherein the steam (40) flows freely into the sterilizer, flows freely within the sterilizer, and flows freely out of the sterilizer as exit steam (50); and(b) channelling the exit steam (50) to a secondary steam turbine (T2) to produce auxiliary power, the secondary steam turbine (T2) producing turbine exhaust steam (60) and turbine condensate as waste.

2. The method according to Claim 1, wherein power from the primary steam turbine (T1) is channelled to an external power grid and the auxiliary power from the secondary steam turbine (T2) is used internally for the oil palm mill.

3. The method according to Claim 1 , wherein power from the primary steam turbine (T1 ) is channelled to an independent power user and the auxiliary power from the secondary steam turbine (T2) is used internally for the oil palm mill.

4. The method according to Claim 1, wherein the auxiliary power from the secondary steam turbine (T2) to is channelled to an external grid for non-oil palm mill use.

5. The method according to Claim 1, wherein the auxiliary power from the secondary steam turbine (T2) to is channelled to an independent power user.

6. The method according to Claim 1, wherein steam from the boiler (10) is channelled to the secondary steam turbine (72).

7. The method according to Claim 1, wherein steam from the primary steam turbine (T1) is channelled to the secondary steam turbine (T2).

8. The method according to Claim 1, wherein steam from the Back Pressure Receiver (20) is channelled to the secondary steam turbine (T2).

9. The method according to Claim 1 , wherein the turbine exhaust steam (60) from the secondary steam turbine (T2) is recycled back to the Back Pressure Receiver (20).

10. The method according to Claim 1, wherein the turbine condensate from the secondary' steam turbine (T2) is recycled back to the Back Pressure Receiver (20).

11. The method according to Claim 1 , wherein the turbine condensate from the secondary' steam turbine (T2) is recycled back to the mill for heating use.

12. The method according to Claim 1, wherein the exit steam (50) is relayed to a second Back Pressure Receiver (70) prior to delivery to the secondary steam turbine (T2).

13. The method according to any one of the preceding Claims, wherein the turbine exhaust steam (60) from the secondary steam turbine (T2) is used tor decanter cake drying.

14. The method according to any one of Claims 1 to 12, wherein the turbine exhaust steam (60) from the secondary steam turbine (T2) is used for heavy-phase liquid drying.

15. The method according to any one of Claims 1 to 12. wherein the turbine exhaust steam (60) from the secondary steam turbine (T2) is used for drying POME.

16. A system for generating auxiliary power in an oil palm mill having a boiler (10), a primary steam turbine (T1) for power generation, and a Back Pressure Receiver (20), wherein there is provided at least one sterilizer (30a, 30b, 30c, 30d) that is configured for free inflow of steam (40), free internal flow of steam (40), and free outflow of steam (40) as exit steam (50), and a secondary steam turbine (T2) to produce auxiliary power characterized in that, the secondary steam turbine (T2) is in fluid communication with the exit steam (50) to produce the auxiliary power.

17. The system according to Claim 16, wherein the secondary steam turbine (T2) is in fluid communication with the boiler (10).

18. The system according to Claim 16, wherein the secondary steam turbine (T2) is in fluid communication with the Back Pressure Receiver (20).

19. The system according to Claim 16, wherein the secondary steam turbine (T2) is in fluid communication with the primary steam turbine (T1).

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