GB2169423A - Power supply system - Google Patents

Power supply system Download PDF

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Publication number
GB2169423A
GB2169423A GB8600115A GB8600115A GB2169423A GB 2169423 A GB2169423 A GB 2169423A GB 8600115 A GB8600115 A GB 8600115A GB 8600115 A GB8600115 A GB 8600115A GB 2169423 A GB2169423 A GB 2169423A
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Patent type
Prior art keywords
steam
power supply
supply means
means
boilers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8600115A
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GB2169423B (en )
GB8600115D0 (en )
Inventor
Barry M Couldridge
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Abco Technology Ltd
Original Assignee
* ABCO TECHNOLOGY LIMITED
ABCO TECHNOLOGY LIMITED
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22STEAM GENERATION
    • F22BMETHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B35/00Control systems for steam boilers
    • F22B35/008Control systems for two or more steam generators

Abstract

Power supply means using a plurality of steam-raising boilers 1-4 serving a number of steam using facilities 10a, 10b with provision to shed one or more of the steam using facilities when the steam requirement represents short term change from a pre-determined steam load profile, thus preventing the inefficiency of starting up an additional one of the boilers for a short operating period on low load. <IMAGE>

Description

SPECIFICATION Power supply system This invention relates to power supply systems, and in particular to a power supply system using boilers for raising steam or hot water, hereinafter jointly referred to as steam raising boilers.

With the increased consciousness of the need for energy savings and cost savings, it has been recognised generally that improvements need to be made in energy usage. Considerable attention has therefore been given to improved energy utilisation and this has resulted in a number of proposals for the management of the so-called "secondary" energy sources, such as the electrical supply. Thus, microprocessor-based systems are known which aim for instance to switch steam and/or lighting loads, acting on manually-entered data such as working hours, with additional inputs from selected sensors around a hospital or factory complex.Such systems are an improvement over previous systems which relied wholly on manual or time switch control-for instance to switch off the lights when a building is vacated; but such proposals did not encompass an integrated energy management system in that they did not suggest interfacing with the steam-raising plant.

One characteristic of steam raising boilers is their inertia when faced with rapid fluctuations in the load they are required to service, so that a small increase in the demand for steam may only be slowly answered. A second characteristic is the low efficiency of boilers having a fluctuating steam load or demand. In the not unusual situation of a hospital or factory complex having three steam raising boilers commissioned, with usually two boilers sufficient to meet the demand and one on "stand by", a relatively small increase in demand could bring the stand-by boiler into operation, perhaps only for a short time, but during this time this boiler runs at a very low and therefore inefficient rate.

It is an object of this invention to provide an integrated energy management system which includes a facility permitting boiler sequencing and load-shedding to meet a predetermined or heuristically derived load profile.

According to our invention we provide power supply means comprising a plurality of steam-raising boilers, at least one steam-user, first monitor means to indicate the steam load for the steam-user, second monitor means to indicate the condition of each of the steam raising boilers, control means to sequence the firing of said boilers so that the steam raised relates to the steam load for the steam-user, and over-ride means to shed part of the steam load for the steam-user when said load fluctuates so as to require firing of an additional boiler.

According to a further feature of the invention we provide boiler monitor means for use in the power supply means as specified hereinbefore which includes a computer having software adapted to correlate input data from the boiler so that the computer emits signals representing control data for the boiler.

According to yet a further feature of the invention we provide a supervisory unit for a power supply means as specified hereinbefore at an installation adapted to receive current information from the said first monitor means, and from the said control means on the current sequencing condition of the boilers, and to compare this information with a predetermined steam profile to effect control of the steam heating and hot water heating for the installation.

Our invention will further be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic outline of an integrated energy management system; and Figure 2 is a schematic layout showing the Director integrated control; in cognate with a "Watchman" boiler monitor unit, governor boiler sequencing unit, with four boilers.

Each of the four boilers 1, 2, 3, 4 is connected to line 5 for its feed water supply and to line 6 for its oil supply (though other boilers may use gas or coai for instance). The oil supply rates and total volumes required are likely to be different for each of the boilers, both because the boilers conventionally each have a different output rating-so that boiler 4 has a single oil burner nozzle assembly 7 whilst boilers 1-3 have two such assemblies; and because one or more of the boilers may be temporarily not required or out of service for maintenance.

Thus the battery comprising the four boilers has a stepped output.

Each of the boilers is connected to steam line 8, serving a number of remotely-located steam-users; each steam user will conventionally have both a different instantaneous and over a selected period of time a different total steam requirement, monitored locally such as at outstations 10a, 10b, the number and location of the outstations being selected to suit the specific installation.

The outstations 10a, 10b are connected by cable 11 to the computer centre 12, which can be remotely located and conventionally comprises a micro-computer 13, keyboard 14, visual display unit 15, disk drive 16 and printer 17. Also coupled to cable 11 are the "Watchman" unit 18 and the governor unit 19.

Whilst the outstations can monitor local conditions, for instance in the heating zones of a building, such as individual or grouped hospital wards, the computer centre 12 can effect control of these zones in response to pre-set parameters and temperature condi tions, both internal and external to the building. Line 20 transmits the signal for the specific zone temperature, line 21 the signal for a heating water flow temperature, line 22 controls a line valve, line 23 controls the pump, and line 24 controls steam into the calorifier.

Other lines can be provided as desired from corresponding sensors.

The "Watchman" boiler monitor unit 18 monitors the overall combustion efficiency of each individual boiler from suitably positioned sensors. Thus, lines 30a, 30b, 30c transmit a signal representing the steam pressure or flow generated respectively at boilers 1, 2, 3 from suitably positioned sensors, whilst line 31 transmits a signal indicating the pressure or flow at one position in steam line 8. Line 32 carries a signal indicating the boil flow rate which can be aggregated by boiler monitor unit 18 to indicate the total consumption over a selected period of time, as can be the water flow rate signal carried by line 33.The unit 18 can receive signals on all aspects of boiler performance, for instance on the gross volume of water evaporated and on the blow downvolume, to permit calculation of the net volume of water evaporated; not only one on the boiler steam pressure but also on the feedwater temperature, the flue gas temperature, the CO2 percentage in the flue, as well as the ambient temperature within the boilerhouse; control parameters can also be monitored, such as the maximum permissible CO2, as well as the oil consumption. The boiler monitor unit 18 can thus monitor, and cause the printer 17 to print out, the basic information in, for instance, a weekly boiler performance report, as well as calculated information such as steam/fuel ratios and operating efficiencies.

The boiler sequencing or governor unit 19 is connected to boiler monitor unit 18, and enables the boilers to be sequenced in relation to the load, and so that loads can be shed.

The sequencing and shedding is effected by boiler monitor unit 18 under the control of governor unit 19, and may require modications to the hardware and software of boiler monitor unit 18 in known manner. If the steam load is to be reduced over an extended period then boiler 4 may be fired instead of one of boilers 1, 2, 3 whereas if the steam load is to be increased substantially over an extended period boiler 4 may be fired in addition to one or more of boilers 1, 2, 3. If however the steam load would require one of the boilers to run at low load, then loads can be shed-for instance that of one or more of the hot water calorifiers such as that connected to line 24.

The system will allow all such low priority loads in one zone to be shed, or can shed one or more in a number of widely spaced zones, to a predetermined pattern. Thus a priority system of shedding loads can be followed, depending upon the size of load to be shed, and for the required length of time. In a survey conducted to determine the usefulness of this invention, the inventor has found that in a hospital environment no less than 30% of the steam load can be shed, to avoid firing of extra boilers for short term low steam requirements, since much of the steam generated is for domestic quarters, social clubs and similar amenities of lower priority and usually having a large thermal mass.

The sequencing of boilers 1, 2, 3 and 4 will be effected in comparison with a predetermined or heuristically derived heating profile, this profile representing the anticipated boiler loading. Such a profile will generally comprise two parameters, the first representing the base load required for process applications, and the second the heating load required to maintain a given internal building temperature for various external ambient temperatures.For any comparable time-slice whilst the first parameter will usually alter only marginally, for instance only if there is a plant breakdown, the second parameter is likely to vary widely, for instance the steam loading required to heat a building to 20"C by 9 am. when the ambient temperature is 0 C as opposed to when it is 20"C. Once the profile for a given time segment has however been set, then changes in demand, particularly those requiring boiler sequencing, can be met if the profile indicates that the extra demand is likely to be shortterm only, by shedding loads-generally heating loads.A typical case is an extra load at 4 pm which under current arrangements brings in an extra boiler even though the need to heat office quarters will reduce at 5 pm; with this invention a less-essential load will be shed to avoid the inefficient and costly firing of an extra boiler, or of closing down a smailer boiler to fire up a larger boiler, for what will prove from the profile to be only a short term demand.

The supervisory system has a heuristic capability which permits a running record of the profiles, and the real-time departures therefrom, so permitting continual closer approximations of the profile parameters to actual day-to-day requirements.

Whilst it has previously been the practice to sequence boilers in response to the aggregate head of pressure generated, and to control the heating zones from the outstations, heretofore these controls have not been integrated in the interest of greater fuel economy and more efficient operation of the boiler plant. An advantage of this invention is that the requirement for a "stand-by" boiler is greatly reduced.

Individual boiler control will conveniently be through its own control panel.

In the schematic diagram of Fig. 2, the supervisory system 56 and the associated plant room controls 45a, 45b, 45c...45z, comprises the "Director" (in the dotted box) re ceiving operating and current condition information from the boiler monitor unit 18 and the boiler sequencing unit 19, to give overall control of the load system heating and of boiler sequencing, and permitting additional boiler output (to be brought in) only if the forward heating profile indicates a sustained need for extra steam. The plant room control 45a is associated with plant room 34a, and the other controls similarly with their respective plant rooms.

We thus provide an integrated energy management system, matching steam loads to efficient boiler operation. Whilst shedding electrical loads is still an available option, the control of steam loads as herein described is the route most likely to secure consistent energy savings.

An advantage for our integrated system is that a prediction of the anticipated load fluctuations is automatically received by the boiler plant, which can then respond in the most efficient and economical way possible. Because of the thermal inertia inherent in even the most efficient steam or hot water boilers, without our predictive loading much fuel will be wasted. The beneficial effects of our predictive loading are even further enhanced by the ability of the system to shed loads in order to achieve intelligent boiler sequencing.

Thus where four steam raising boilers are installed to meet the requirements of a large hospital complex, it would be normal for three of the four boilers to be capable of meeting the maximum steam demand, while one of the four boilers would be out of service undergoing maintenance; there will be occasions when two of the three "in-service" boilers were meeting the demand and the third was being kept "on standby" in order to meet unexpected load increases, and in this situation even a small increase in demand for steam or hot water would bring the standby boiler on line, probably to run at a very low and inefficient rate. Our integrated energy management system would assess the importance of the new load demand and consider it in conjunction with all of the other existing loads.

Because of its inbuilt knowledge of the operational profile of the total heating system, our integrated energy management system automatically reviews this new load in relation to all of the other activities currently being managed as well as those due to be gained, to be offset against those due to be lost, and in order to prevent the necessity for the third boiler to be brought on line would seek to shed some loads in other areas. In these circumstances once the operational profile has been fully established for selected installations, it has been shown unnecessary to have the "third" boiler, even on a standby basis.

The intelligent and integrated system described above can be considered as a true energy management system, in contrast to earlier systems using this appellation which used microprocessor technology but only to do relatively mundane tasks which could alternatively be performed by arrays of timers and thermostats. In contrast we provide an interface between the heat sourace i.e. the boiler plant, and the control of the heating zones.

In any particular installation the totally integrated approach to energy management described above can be achieved in three distinct phases: 1. Monitor boiler plant efficiency ("Watch man''), 2. Close the loop to sequence-control the boilers ("Governor"), 3. The control of all the heating zones ("Director").

These three phases can be installed in the sequence 1, 2, 3 or alternatively 3, 2, 1.

However the most logical course is to install the monitor first in order to provide a bench mark against which future gains in efficiency in fuel savings may be judged.

An important feature of the "Watchman" boiler monitor unit 18 is the ability automatically to produce management information. This feature aims to solve a problem for organisations such as the DHSS which have an established manual management control system in operation, providing for instance weekly analyses of overall boiler plant efficiency. The existing system e.g. DHSS control form 2" has been designed for manual compilation and involves several hours of tedious work to produce. Software has been developed and incorporated into the "Watchman" boiler monitor unit to enable it to produce "control form 2" or equivalents automatically, e.g. at 2400 hours on Sunday, or on demand at the touch of a button, and this has proved an important enhancement which it will be understood can be used even before our "Director" system (item 3 of the previous paragraph) is installed.

Claims (27)

1. Power supply means comprising a plurality of steam-raising boilers, at least one steam-user, first monitor means to indicate the steam load for the steam-user, second monitor means to indicate the condition of each of the steam raising boilers, control means to sequence the firing of said boilers so that the steam raised relates to the steam load for the steam-user, and over-ride means to shed part of the steam load for the steamuser when said load fluctuates so as to require firing of an additional boiler.
2. Power supply means as claimed in Claim 1 in which the steam raising boilers are of different capacity so that said boilers are stepped in output.
3. Power supply means as claimed in Claim 1 or Claim 2 in which said one steam user includes a process demand and a heating demand.
4. Power supply means as claimed in Claim 3 in which said process demand has a constant value over a predetermined time period each day.
5. Power supply means as claimed in Claim 3 or Claim 4 in which said heating demand varies about one level during one part of a 24 hour day and varies about a second level during the remainder of said day, said second level being below said first level, said second level including a time period between sunset and sunrise.
6. Power supply means as claimed in any of claims 1 to 5 in which the first monitor means is responsive to specific zone temperature.
7. Power supply means as claimed in any of claims 1 to 5 in which the first monitor means is responsive to heating water flow temperature.
8. Power supply means as claimed in any of claims 1 to 5 in whih the first means is responsive to the steam flow to a calorifier.
9. Power supply means as claimed in any of claims 1 to 8 in which the second monitor means is responsive to the steam pressure generated in each of the boilers.
10. Power supply means as claimed in any of claims 1 to 8 in which the second monitor means is responsive to the steam pressure or flow at a selected position in the common steam output line from the boilers.
11. Power supply means as claimed in any of claims 1 to 8 in which the second monitor means is responsive to steam flow at a selected position in the common steam output lines from the boilers.
12. Power supply means as claimed in any preceding claim in which the control means acts through the control panel of each boiler.
13. Power supply means as claimed in any preceding claim in which the system operating characteristics are monitored in real time.
14. Power supply means as claimed in claim 13 in which a characteristic monitored is the degree of opening of individual line valves.
15. Power supply means as claimed in Claim 13 in which a characteristic monitored is the oil flow rate to each boiler.
16. Power supply means as claimed in Claim 13 in which a characteristic monitored is the water flow volume to each boiler.
17. Power supply means as claimed in Claim 13 in which a characteristic monitored is the percentage CO2 in the flue gas.
18. Power supply means as claimed in any of claims 13 to 17 in which the monitored characteristic is continually recorded.
19. Power supply means as claimed in Claim 18 in which the monitored characteristic is communicated to a data bank.
20. Power supply means as claimed in Claim 19 in which the monitored characteristic is stored for subsequent visual display by a printer.
21. Power supply means as claimed in Claim 20 in which the printer operates at preselected times of day.
22. Power supply means as claimed in Claim 19 or Claim 20 in which the data bank is part of a computer record, the computer being programmed to combine preselected monitored characteristics and to calculate a resultant value.
23. Power supply means constructed and arranged substantially as herein described with reference to the accompanying drawing.
24. Power supply means comprising a plurality of steam raising boilers, at least one steam user, monitor means to provide an indication of a changed steam requirement of the steam user, control means to vary the aggregate output from the boilers in response to said indication, and means to override said control means when said indication represents only a short term changed steam requirement from a pre-determined steam usage profile.
25. A boiler monitor means for use in the power supply means as claimed in any preceding claim which includes a computer having software adapted to correlate input data from the boiler so that the computer emits signals representing control data for the boiler.
26. Boiler monitor means as claimed in claim 25 in which the said signals are adapted to effect a print-out of numerical values on a pre-printed form fed to a printer.
27. A supervisory unit for a power supply means as claimed in any of claims 1-24 at an installation and adapted to receive current information from the said first monitor means, and from the said controls means on the current sequencing condition of the boilers, and to compare this information with a predetermined steam profile to effect control of the steam heating and hot water heating for the installation.
GB8600115A 1985-01-03 1986-01-03 Power supply system Expired GB2169423B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8500065A GB8500065D0 (en) 1985-01-03 1985-01-03 Power supply system

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GB8600115D0 true GB8600115D0 (en) 1986-02-12
GB2169423A true true GB2169423A (en) 1986-07-09
GB2169423B GB2169423B (en) 1988-03-09

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GB8500065A Pending GB8500065D0 (en) 1985-01-03 1985-01-03 Power supply system
GB8600115A Expired GB2169423B (en) 1985-01-03 1986-01-03 Power supply system

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002048615A2 (en) * 2000-12-15 2002-06-20 Honeywell International Inc. Fault-tolerant multi-node stage sequencer and method for energy systems

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1486569A (en) * 1974-09-03 1977-09-21 Babcock & Wilcox Co Control system for a power producing unit
EP0023254A2 (en) * 1979-07-02 1981-02-04 Sangamo Weston, Inc. Method and apparatus for controlling power distribution of an electric utility
GB2069729A (en) * 1980-02-19 1981-08-26 Honeywell Inc Control system for electrical heating/cooling apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1486569A (en) * 1974-09-03 1977-09-21 Babcock & Wilcox Co Control system for a power producing unit
EP0023254A2 (en) * 1979-07-02 1981-02-04 Sangamo Weston, Inc. Method and apparatus for controlling power distribution of an electric utility
GB2069729A (en) * 1980-02-19 1981-08-26 Honeywell Inc Control system for electrical heating/cooling apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WO A1 82/03133 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002048615A2 (en) * 2000-12-15 2002-06-20 Honeywell International Inc. Fault-tolerant multi-node stage sequencer and method for energy systems
WO2002048615A3 (en) * 2000-12-15 2003-01-09 Honeywell Int Inc Fault-tolerant multi-node stage sequencer and method for energy systems
US6745085B2 (en) 2000-12-15 2004-06-01 Honeywell International Inc. Fault-tolerant multi-node stage sequencer and method for energy systems

Also Published As

Publication number Publication date Type
GB2169423B (en) 1988-03-09 grant
GB8500065D0 (en) 1985-02-13 application
GB8600115D0 (en) 1986-02-12 application

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