This case pertains to a high-pressure cylinder pressure ratio cogeneration system for steam turbines, aimed at improving upon existing technology to solve specific technical challenges. The improvements are as follows: setting the rated pressure ratio of the high-pressure cylinder (HP) as re, and the continuous operating allowable pressure ratio as [r], with a requirement that [r]/re≥1.3. The technical effect achieved is that under high-pressure extraction steam conditions, due to the above ratio relationship, the pressure value at the exhaust port of the high-pressure cylinder during extraction can be reduced to near or equal to the heating demand pressure value of the heat network. This reduction minimizes the disparity between high-pressure steam pressure and the heat network’s demand pressure, or directly aligns the high-pressure extraction steam parameters with the heating demand parameters of the heat network, thus effectively preventing the wastage of potential energy in high-pressure steam.
The present invention underwent four office actions. The first and second office actions concluded that this invention is not inventive; the third office action concluded that the specification was not fully disclosed; and the fourth office action concluded that this invention had a problem of duplicate authorization. The problems identified in the first three office actions were particularly challenging and complex to address. However, our agent relied on exceptional professional ability and logical argumentation, systematically addressed these issues. Ultimately, this led to the invention receiving its patent authorization.
In the first office action, the examiner pointed out that none of the claims demonstrated inventiveness and relied on just one comparative document for assessing novelty and inventiveness. The examiner believed that the comparative document D1 disclosed most of the technical features of the claim except for “the rated pressure ratio of the high-pressure cylinder (HP) defined as re, and the continuous operating allowable pressure ratio as [r], with [r]/re≥1.3”. The examiner contended that even though D1 did not disclose this specific ratio, it did describe a scheme using an extraction pipe for high-pressure extraction steam. By incorporating a certain safety factor and using a cooling and pressure-reducing device, D1 aimed to align the extraction parameters with the actual heating demand parameters of the heat network. The present invention raises the continuous operating allowable pressure ratio [r] of the high-pressure cylinder and makes [r]/re≥1.3, so there is no need to set a cooling and pressure-reducing device. The examiner believed that this invention only adjusts a certain safety factor, and D1 provides a technical guidance for adjusting the safety factor.
In fact, D1 contains an extensive description with complex structural components. When replying to the first office action, the agent keenly realized that the present invention is substantially different from D1, and directly grasped the key point. Our agent argued that although D1 adopted a high-pressure extraction steam scheme, which was the same as that of the present invention, to solve the same technical problem, D1 adopted a cooling and pressure-reducing device, while the present invention based on a continuous operating allowable pressure ratio [r] of the high-pressure cylinder (HP) and a rated pressure ratio re of the high-pressure cylinder (HP), and satisfied the following relationship [r]/re≥1.3, so the two use different technical means.
In the second office action, the examiner reiterated points raised in the first office action and further indicated that this invention merely limited a ratio relationship. However, it failed to specify what specific methods or means could overcome the existing technical prejudice and realize [r]/re≥1.3. Therefore, the examiner believed that this invention simply adjusted a particular safety factor as suggested in D1.
When responding to the second office action, our agent first described the relationship between the continuous operating allowable pressure ratio [r], and the strength of blades and the efficiency of units during pure condensation gas operation. That is, a higher continuous operating allowable pressure ratio [r] is adopted to ensure benefits, but the strength of blades requires a high level, which will result the efficiency of units to be relatively low during pure condensation gas operation. In order to achieve a relative balance between benefits and the efficiency of units during pure condensation gas operation, the continuous operating allowable pressure ratio [r] used in existing technologies must be lower than 1.3 times the rated pressure ratio re, that is, [r]/re<1.3. Therefore, D1 needs to adopt a cooling and pressure-reducing device to solve the existing problems. The present invention overcomes this technical prejudice, and the technical problem can be directly solved by setting [r]/re≥1.3 without setting a cooling and pressure-reducing device. Therefore, D1 did not provide positive technical guidance, and the present invention adopted unconventional design methods to achieve the economy of the steam turbines under heating conditions, simplify the system, and improve the versatility of the cogeneration steam turbine units.
The examiner subsequently issued the third office action, in which the examiner basically accepted our agent’s arguments regarding the second office action, but raised a new issue, indicating that the present specification had a substantial defect of insufficient disclosure. Specifically, the application only presented the ratio relationship [r]/re≥1.3 but did not elaborate on the specific means (such as employing special designs or using high-performance materials) necessary to overcome the existing technical prejudice and achieve [r]/re≥1.3.
In the third response, the agent began by adopting the perspective of a technician in the field to elucidate the factors influencing the pressure ratio of the high-pressure cylinder. These factors include the strength, width, and material of the blades, and the efficiency of the units under pure condensing steam operation. As these parameters are adaptable and controllable by technicians in the field, they can achieve the desired pressure ratio of the high-pressure cylinder by increasing blade width, upgrading blade materials, or other standard methods, taking into account a certain safety factor, thereby meeting either [r]/re<1.3 or [r]/re≥1.3. Secondly, our agent emphasized that the existing technical prejudice aimed to balance the efficiency of pure condensation steam, and adopted a lower continuous operating allowable pressure ratio. In contrast, the present invention adopts an opposite approach. It resolves the technical issues without necessitating a cooling and pressure-reducing device.
In the fourth office action, the examiner acknowledged these arguments but raised an issue regarding duplicate authorization. Following the submission of documents by our agent addressing this issue, the invention was eventually granted a patent authorization.