JPH0318839Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a control system for combustion equipment mainly used in small boilers.

[Technical background of the invention and its problems] When controlling boiler combustion, every possible measure must be taken to prevent accidents caused by accumulation of unburned gas, such as backfires and gas explosions. Therefore, in order to prevent residual unburned oil and leaked oil during stoppage from vaporizing and causing residual heat and gas explosion at the time of ignition, a control method that performs a pre-purge before an ignition attempt and a post-purge after a combustion stop has been developed. As shown in Figure 4, combustion control (Q is heat demand) is generally performed in the order of pre-purge (PR), ignition try (IG), combustion (CO), and post-purge (PO). However, with this conventional method, even if there is a heat demand during post-purge, pre-purge starts from that point on, so there is a delay in following the post-purge load.Furthermore, since the purge is performed more than necessary, the inside of the furnace is cooled and thermal Loss is also large. In particular, in small boilers that have a small amount of steam and water, this delay causes the supply steam pressure to drop rapidly, causing problems such as problems on the load side.

[Effect of the invention] This invention was made in view of the above circumstances, and when there is a heat request during post purge,
A combustion control system that improves load followability and reduces heat loss due to purging by taking into account the purge time during which the purge is performed for a predetermined pre-purge time after combustion stops, and then immediately transitions to ignition try. The purpose is to provide

[Summary of the invention] In order to achieve the above purpose, this system uses a control system that includes pre-purge (PR), ignition try (IG), combustion (CO), and post-purge (PO) stages, and uses heat during post-purge. When a request (Q) is received, if the time (t) from the start of post-purge to the heat request is the same as or longer than the pre-set pre-purge time T, the ignition trial is started at the same time as the heat request, When the time (t) from the start of the post-purge until the heat request is smaller than the pre-purge time (T), the pre-purge is performed for the time (T-t) from the heat request, and then the ignition try is performed. It is characterized by what it did.

[Embodiments of the invention] This invention will be described below with reference to the drawings. 1st
Figure 2 is an explanatory diagram of the configuration of the control system of this invention, Figure 2 is a time chart of combustion control when the heat demand is greater than the pre-purge time, and Figure 3 is a time chart of combustion control when the heat demand is less than the pre-purge time. It is a time chart.

Reference numeral 1 in the drawings denotes a boiler, and 2 denotes a heat demand detector consisting of, for example, a steam pressure detector or a temperature detector, which sends a heat demand signal to the control device 6. Reference numeral 3 denotes a blower for supplying air for pre-purge, post-purge and combustion to the boiler, and is operated in response to a signal from the control device 6. 4 is a fuel controller which operates in response to a signal from a control device 6; 5
is an ignition device, which operates in response to a signal from the control device 6.

In the above configuration, when the control device 6 receives a heat request signal from the heat request detector, it operates the blower 3 to perform pre-purge (PR) for a set time (T), and then operates the ignition device 5 for a set time (T). _t2 ) At the same time, a fuel controller (not shown) is activated to perform an ignition trial. After the ignition attempt, the ignition device 5 stops, continues combustion, and continues into steaming operation. When the heat demand from the heat demand detector disappears, the fuel controller is closed to stop combustion, and post-purging of only the blower is performed thereafter.

If a heat request is made again during this post-purge, if the time of the heat request (time t ₁ from the start of post-purge to the time of heat request) has elapsed after a time equivalent to the pre-set pre-purge time (T). , as shown in FIG. 2, the pre-purge is omitted and the process shifts to an immediate ignition try, and combustion is started. On the other hand, if the heat request time (time t ₁ from the start of post-purge to the heat request time) is before the elapse of the pre-purge time (T), as shown in _FIG . Perform a pre-purge and then try ignition to move to combustion.

[Effects of the device] This device is configured as described above, and when a heat request is made during post-purge, if the purge has been carried out for the required pre-purge time from the start of post-purge, the ignition trial can be started immediately. This eliminates the combustion delay caused by extra purges, which is the case with conventional methods, and improves load follow-up, and eliminates heat loss caused by extra purges, making it especially suitable for small boilers with small amounts of steam and water. It is valid. Moreover, since at least a pre-purge time is secured for purging after combustion has stopped, there is no risk of gas explosion due to insufficient ventilation.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing an example of the use of the control system of this invention, Fig. 2 is a time chart showing an example of combustion control, Fig. 3 is a time chart showing another example, and Fig. 4 is a conventional diagram. FIG. 2 is a time chart showing a combustion control system of the present invention. 1 is a boiler, 2 is a heat demand detector, 3 is a blower, 4 is a fuel controller, 5 is an ignition device, and 6 is a control device.

Claims (1)

[Scope of utility model registration request] In a control system that includes pre-purge (PR), ignition try (IG), combustion (CO), and post-purge (PO) stages, if there is a heat demand (Q) during post-purge, the heat demand will start from the start of post-purge. When the time (t) from the start of the post-purge to the heat request is the same as or longer than the pre-purge time (T), the ignition trial is started at the same time as the heat request, and the time (t) from the start of the post-purge to the heat request is the same as the pre-purge time (T). Combustion control system for a small boiler, characterized in that it is equipped with a control means that operates to perform a pre-purge for a time (T-t) from the heat request time and then shift to an ignition try when the pre-purge time is shorter than the pre-purge time (T). .