CN114011863A - Stack type thermal desorption technology - Google Patents
Stack type thermal desorption technology Download PDFInfo
- Publication number
- CN114011863A CN114011863A CN202111237764.9A CN202111237764A CN114011863A CN 114011863 A CN114011863 A CN 114011863A CN 202111237764 A CN202111237764 A CN 202111237764A CN 114011863 A CN114011863 A CN 114011863A
- Authority
- CN
- China
- Prior art keywords
- soil
- extraction
- heating
- polluted
- pipe
- 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.)
- Pending
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09C—RECLAMATION OF CONTAMINATED SOIL
- B09C1/00—Reclamation of contaminated soil
- B09C1/06—Reclamation of contaminated soil thermally
- B09C1/065—Reclamation of contaminated soil thermally by pyrolysis
Abstract
The invention discloses a heap type thermal desorption technology, which comprises the following steps: s1: digging out soil in the polluted area, and stacking the original site to a restoration area after the dug soil is short-cut; s2: screening the contaminated soil; s3: paving polluted soil with a certain thickness in the restoration area, and paving a heating pipe, an extraction pipe and a temperature and pressure measuring sensor component on the top of the polluted soil; s6: carrying out cement hardening treatment on the periphery and the top of the outer wall of the soil body unit; s7: and (4) installing pipeline equipment and constructing a related matched system on the outer wall of the soil body. According to the heap type thermal desorption technology, the adaptive heating pipe and the extraction pipe are selected, so that the safety during soil remediation is guaranteed, the pertinence and the effectiveness are achieved, the energy waste is avoided, and the rapid removal and the secondary pollution control of soil pollutants under the thermal desorption condition are realized through the extraction system of the pollutants under the high-temperature condition, which comprises the extraction pipe form and the arrangement mode.
Description
Technical Field
The invention relates to the field of soil remediation, in particular to a heap type thermal desorption technology.
Background
Soil is one of basic elements forming an ecological system, is a material foundation on which human beings live, is an important substance indispensable to life activities on the earth, and along with the aggravation of industrial pollution and the wide use of chemical substances, the organic pollution in the soil is increasingly serious, typical organic pollutants in the soil comprise benzene series, petroleum hydrocarbon, polycyclic aromatic hydrocarbon, pesticide, polychlorinated biphenyl, organic halide and the like, the existence of the pollutants in the soil environment can generate serious adverse effects on nearby human bodies and the surrounding environment, the existing indigenous thermal desorption technology and equipment fall behind, the imported cost from abroad is high, a plurality of limitations exist, the safety and the cost of the existing technical process are low, no good protective measures are provided when the polluted soil is repaired, the temperature of the polluted soil is too high, and workers cannot approach to perform subsequent repair on the polluted soil, nor is the escape of contaminants organized.
Disclosure of Invention
The invention mainly aims to provide a heap thermal desorption technology, which can effectively solve the problems in the background technology.
In order to achieve the purpose, the invention adopts the technical scheme that:
a heap type thermal desorption technology comprises the following operation steps:
s1: carrying out paying-off measurement on the soil in the polluted area, determining the boundary of the soil to be restored, marking out the polluted area, digging out the soil in the polluted area, and stacking the original site to the restoration area after the dug soil is short refuted;
s2: screening the polluted soil, and taking out the construction waste in the polluted soil;
s3: paving polluted soil with a certain thickness in the restoration area, and paving a heating pipe, an extraction pipe and a temperature and pressure measuring sensor component on the top of the polluted soil;
s4: continuously paving polluted soil above the heating, extracting and other components;
s5: repeating the steps of S3 and S5, and laying the polluted soil and the components in layers until the polluted soil and the components are laid to the set height;
s6: carrying out cement hardening treatment on the periphery and the top of the outer wall of the soil body unit;
s7: and (4) installing pipeline equipment and constructing a related matched system on the outer wall of the soil body.
Preferably, the heating mode can adopt fuel oil combustion heating, fuel gas combustion heating or electric heating, and specifically needs to be selected according to comprehensive consideration of soil pollution characteristics, restoration time, heating target temperature, energy supply conditions and the like, the heating target temperature is set to meet the requirement that all target pollutants can be volatilized and removed under the action of the extraction unit under the set temperature, and the target heating temperature and the heating time duration are determined and comprehensively determined by integrating factors such as small-scale test effects, restoration construction periods, economy, safety and the like.
Preferably, the effective action ranges of the heating pipes and the extraction pipes during working can be comprehensively determined and obtained according to the experience of similar project data, soil permeability and heat conductivity, the number and the distribution positions of the heating pipes and the extraction pipes can be determined according to the information such as the unit size of soil, the effective ranges of the heating pipes and the extraction pipes during working, the arrangement mode, the soil pollution condition, the target effect of remediation treatment, the heating time and the like, the number ratio of the heating pipes to the extraction pipes is generally 1:1-4:1, the heating pipes can be distributed in the form of regular triangles or regular hexagons and the like, the extraction pipes can be distributed at the central positions of regular triangles or regular hexagons formed by the vertices of the heating pipes or in the associated positions of the heating pipes and the heating pipes, the heating pipes and the extraction pipes are uniformly distributed in the whole soil unit and need to be distributed in a horizontal mode, the pipe fittings are horizontally arranged at intervals in the length and width direction of the pile body, the spacing distance should be such that all soil is within the effective working range of the heating and extraction pipes.
Preferably, the diameter, thickness and material of the heating pipe are determined according to installation method, working temperature, contaminated soil characteristics and other factors.
Preferably, the extraction pipe comprises a pipeline and extraction power equipment, the height of the extraction pipe is limited by the height of the pile body, the extraction pipe is generally in a horizontal form and can be placed in parallel with the heating pipe, the extraction pipe comprises a wellhead protection device, a well pipe and a filter screen, a small hole is formed in the pipe wall of the well pipe, the metal filter screen is wrapped outside the well pipe, the periphery of the well pipe is filled with filter materials, the well pipe is made of high-temperature-resistant and corrosion-resistant pollutant materials, the extraction unit is required to maintain a certain temperature level, and the surface separation is arranged outside the soil body to enable the soil body to be completely closed.
Preferably, the extraction rate and the vacuum degree required by extraction are determined according to the size of the repair area, the pollutant property, the soil permeability and the like, and a proper vacuum device is selected.
Preferably, the extraction pipe should avoid the leakage of the polluted gas to the atmosphere to cause secondary pollution, a surface blocking anti-seepage measure should be adopted for the soil body, negative pressure design is carried out on the extraction pipe to ensure that the inside of the soil body is in a negative pressure state during the operation of the extraction pipe, continuous and stable operation of the extraction power equipment is ensured, full sealing of the extraction pipeline is ensured, the leakage of the polluted gas outside is prevented, the surface blocking should cover the outside of the whole soil body, the blocking material should have good anti-seepage and heat-insulating properties, the thickness of the concrete heat-insulating layer is generally 10-60 cm, and the temperature of the outside of the pile body should be ensured to be not higher than 60 ℃ after the surface blocking.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, through the closed treatment of the extraction pipeline, the leakage of the polluted gas can be effectively prevented, the secondary pollution of the polluted gas to the atmosphere can be effectively avoided, the heat preservation of the pile body can be effectively realized through adopting a surface separation anti-seepage measure to the soil body, the permeation of the pollutant can be prevented, the high-temperature scald caused by the approach of peripheral constructors can also be avoided, the safety and the cost in the process of repairing the soil can be ensured through selecting the adaptive heating pipe and the extraction pipe, the pertinence and the effectiveness are also realized during the repair engineering, the waste of energy sources is avoided, and the rapid removal and the secondary pollution control of the soil pollutant under the thermal desorption condition are realized through the pollutant extraction system which is suitable for the high-temperature condition and comprises the extraction pipe form and the arrangement mode.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention relates to a heap type thermal desorption technical process, which comprises the following steps:
s1: carrying out paying-off measurement on the soil in the polluted area, determining the boundary of the soil to be restored, marking out the polluted area, digging out the soil in the polluted area, and stacking the original site to the restored area after short refuting of the excavated soil.
S2: and (4) screening the polluted soil, and taking out the construction waste in the polluted soil.
S3: the method comprises the steps of paving polluted soil with a certain thickness in a restoration area, paving a heating pipe, an extraction pipe and a temperature and pressure measuring sensor assembly on the top of the polluted soil, and determining the diameter, thickness and material of the heating pipe according to factors such as an installation method, working temperature and polluted soil characteristics.
S4: the polluted soil is continuously paved above the components such as heating and extraction, the extraction pipe comprises a pipeline and extraction power equipment, the height of the extraction pipe is limited by the height of a pile body, the extraction pipe is generally in a horizontal form and can be placed in parallel with a heating pipe, the extraction pipe comprises a wellhead protection device, a well pipe and a filter screen, a small hole is formed in the pipe wall of the well pipe, the metal filter screen is wrapped outside the well pipe, the periphery of the well pipe is filled with filter materials, the well pipe is made of high-temperature-resistant and corrosion-resistant pollutant materials, the extraction unit is required to maintain a certain temperature level, and the soil body is completely sealed by arranging surface separation outside the soil body.
S5: and repeating the steps of S3 and S5, laying the polluted soil and assemblies in layers until the polluted soil and assemblies are laid to a set height, wherein the extraction pipe is required to avoid secondary pollution caused by leakage of polluted gas to the atmosphere, a surface blocking and seepage-proofing measure is adopted for the soil body, negative pressure design is carried out on the soil body to ensure that the interior of the soil body is in a negative pressure state when the extraction pipe runs, the extraction power equipment is required to be ensured to continuously and stably run, the extraction pipeline is ensured to be fully closed, leakage of the polluted gas is prevented, the surface blocking is required to cover the exterior of the whole soil body, the blocking material is required to have good seepage-proofing and heat-insulating properties, the thickness of the concrete heat-insulating layer is generally 10-60 cm, and the temperature of the exterior of the pile body is required to be not higher than 60 ℃ after the surface blocking.
S6: and carrying out cement hardening treatment on the periphery and the top of the outer wall of the soil body unit.
S7: the method comprises the steps of installing pipeline equipment on the outer wall of a soil body and building a related matched system, wherein the heating mode can be fuel oil combustion heating, fuel gas combustion heating or electric heating, and specifically needs to be selected according to comprehensive consideration of soil pollution characteristics, restoration time, heating target temperature, energy supply conditions and the like, the heating target temperature is set to meet the requirement that all target pollutants can be volatilized and removed under the action of an extraction unit under the set temperature, the target heating temperature and the heating duration are determined, the factors such as comprehensive small test effect, restoration period, economy, safety and the like are comprehensively determined, the effective action range of a heating pipe and an extraction pipe during working can be comprehensively determined and obtained according to the experience of similar project data, the soil permeability and the heat conductivity, and the effective range, the arrangement mode, the soil pollution condition, the effective range, the arrangement mode, the energy consumption and the like of the heating pipe and the extraction pipe during working are comprehensively determined according to the unit size of the soil body, the heating pipe and the extraction pipe working, The quantity and distribution position of the heating pipes and the extraction pipes can be determined according to the target effect of the repair treatment, the heating time and other information, the quantity ratio of the heating pipes to the extraction pipes is generally 1:1-4:1, the heating pipes can be distributed in the form of regular triangles or regular hexagons and the like, the extraction pipes can be distributed in the central positions of the regular triangles or the regular hexagons formed by the heating pipes as vertexes, or the heating pipe and the extraction pipe are closely associated, the whole soil body unit is uniformly distributed on the heating pipe and the extraction pipe, the horizontal arrangement is needed, the pipe fittings are horizontally arranged in parallel along the length and width direction of the pile body at intervals, the interval distance is required to ensure that all the soil is in the effective working range of the heating pipe and the extraction pipe, and determining the extraction rate and the vacuum degree required by extraction according to the size of the repair area, the pollutant property, the soil permeability and the like, and selecting proper vacuum equipment.
According to the invention, through the closed treatment of the extraction pipeline, the leakage of the polluted gas can be effectively prevented, the secondary pollution of the polluted gas to the atmosphere can be effectively avoided, the heat preservation of the pile body can be effectively realized through adopting a surface separation anti-seepage measure to the soil body, the permeation of the pollutant can be prevented, the high-temperature scald caused by the approach of surrounding constructors can also be avoided, the safety and the cost in the process of repairing the soil can be ensured through selecting the adaptive heating pipe and the extraction pipe, the pertinence and the effectiveness are also realized during the repair engineering, the waste of energy sources is avoided, and the rapid removal and the secondary pollution control of the soil pollutant under the thermal desorption condition are realized through the pollutant extraction system which is suitable for the high-temperature condition and comprises the extraction pipe form and the arrangement mode.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Claims (7)
1. A heap type thermal desorption technology is characterized in that: the method comprises the following operation steps:
s1: carrying out paying-off measurement on the soil in the polluted area, determining the boundary of the soil to be restored, marking out the polluted area, digging out the soil in the polluted area, and stacking the original site to the restoration area after the dug soil is short refuted;
s2: screening the polluted soil, and taking out the construction waste in the polluted soil;
s3: paving polluted soil with a certain thickness in the restoration area, and paving a heating pipe, an extraction pipe and a temperature and pressure measuring sensor component on the top of the polluted soil;
s4: continuously paving polluted soil above the heating, extracting and other components;
s5: repeating the steps of S3 and S5, and laying the polluted soil and the components in layers until the polluted soil and the components are laid to the set height;
s6: carrying out cement hardening treatment on the periphery and the top of the outer wall of the soil body unit;
s7: and (4) installing pipeline equipment and constructing a related matched system on the outer wall of the soil body.
2. The bulk thermal desorption process of claim 1, which comprises the following steps: the heating mode can adopt fuel oil combustion heating, fuel gas combustion heating or electric heating, and specifically needs to be selected according to comprehensive consideration of soil pollution characteristics, restoration time, heating target temperature, energy supply conditions and the like, the heating target temperature is set to meet the requirement that all target pollutants can be volatilized and removed under the action of the extraction unit under the set temperature, and the target heating temperature and the target heating time duration are determined and comprehensively determined by integrating factors such as small-test testing effect, restoration period, economy, safety and the like.
3. The bulk thermal desorption process of claim 1, which comprises the following steps: the effective action ranges of the heating pipes and the extraction pipes during working can be comprehensively determined and obtained according to the experience of similar project data, soil permeability and heat conductivity, the quantity and the distribution positions of the heating pipes and the extraction pipes can be determined according to the information such as the unit size of soil, the effective working ranges of the heating pipes and the extraction pipes, the arrangement mode, the soil pollution condition, the target effect of remediation treatment, the heating duration and the like, the quantity ratio of the heating pipes to the extraction pipes is generally 1:1-4:1, the heating pipes can be distributed in the form of regular triangles or regular hexagons and the like, the extraction pipes can be distributed at the central positions of the regular triangles or regular hexagons formed by the vertexes of the heating pipes or in the adjacent association of the heating pipes and the heating pipes, the heating pipes and the extraction pipes are uniformly distributed in the whole soil unit and need to be distributed horizontally, the pipe fittings are horizontally arranged at intervals in the length and width direction of the pile body, the spacing distance should be such that all soil is within the effective working range of the heating and extraction pipes.
4. The bulk thermal desorption process of claim 1, which comprises the following steps: the diameter, thickness and material of the heating pipe are determined according to factors such as installation method, working temperature and polluted soil characteristics.
5. The bulk thermal desorption process of claim 1, which comprises the following steps: the extraction pipe comprises a pipeline and extraction power equipment, the height of the extraction pipe is limited by the height of a pile body, the extraction pipe is generally in a horizontal form and can be placed in parallel with a heating pipe, the extraction pipe is composed of a wellhead protection device, a well casing and a filter screen, a small hole is formed in the pipe wall of the well casing, the metal filter screen is wrapped outside the well casing, filter materials are filled on the periphery of the well casing, the well casing is made of high-temperature-resistant and corrosion-resistant pollutant materials, an extraction unit is required to maintain a certain temperature level, and the soil body is completely sealed by arranging surface separation outside the soil body.
6. The bulk thermal desorption process of claim 1, which comprises the following steps: and determining the extraction rate and the vacuum degree required by extraction according to the size of the repair area, the pollutant property, the soil permeability and the like, and selecting proper vacuum equipment.
7. The bulk thermal desorption process of claim 1, which comprises the following steps: the extraction pipe is used for avoiding secondary pollution caused by leakage of polluted gas to the atmosphere, a surface blocking anti-seepage measure is adopted for a soil body, negative pressure design is carried out on the extraction pipe to ensure that the interior of the soil body is in a negative pressure state during operation of the extraction pipe, continuous and stable operation of extraction power equipment is ensured, full sealing of an extraction pipeline is ensured, leakage of the polluted gas is prevented, the surface blocking material covers the exterior of the whole soil body, the blocking material has good anti-seepage and heat-insulating properties, the thickness of the concrete heat-insulating layer is generally 10-60 cm, and the temperature of the exterior of the pile body is ensured to be not higher than 60 ℃ after the surface blocking.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111237764.9A CN114011863A (en) | 2021-10-25 | 2021-10-25 | Stack type thermal desorption technology |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111237764.9A CN114011863A (en) | 2021-10-25 | 2021-10-25 | Stack type thermal desorption technology |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114011863A true CN114011863A (en) | 2022-02-08 |
Family
ID=80057404
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111237764.9A Pending CN114011863A (en) | 2021-10-25 | 2021-10-25 | Stack type thermal desorption technology |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114011863A (en) |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103203355A (en) * | 2013-04-12 | 2013-07-17 | 江苏大地益源环境修复有限公司 | Ectopic thermal desorption treatment method of polluted soil |
| CN105689382A (en) * | 2016-01-26 | 2016-06-22 | 清华大学 | In-situ remediation system for organic contaminated soil |
| CN106140810A (en) * | 2015-04-02 | 2016-11-23 | 中环循(北京)环境技术中心 | A kind of complex biological treatment system repairing epipodium polycyclic aromatic hydrocarbon pollution |
| CN208341360U (en) * | 2018-05-02 | 2019-01-08 | 北京高能时代环境技术股份有限公司 | A kind of soil remediation thermal desorption heating device |
| CN110614266A (en) * | 2019-09-26 | 2019-12-27 | 中科鼎实环境工程有限公司 | Heap thermal desorption treatment system for repairing organic contaminated soil |
| CN111003792A (en) * | 2019-12-30 | 2020-04-14 | 浙江卓锦环保科技股份有限公司 | In-situ oxidation circulation extraction repair system and repair method for organic polluted underground water |
| CN111215440A (en) * | 2019-10-11 | 2020-06-02 | 广西博世科环保科技股份有限公司 | Organic contaminated soil in-situ alternate electric heating desorption system |
| CN112958612A (en) * | 2021-03-09 | 2021-06-15 | 上海格林曼环境技术有限公司 | In-situ thermal desorption method for repairing organic contaminated soil |
| CN213763426U (en) * | 2020-12-09 | 2021-07-23 | 北京建工环境修复股份有限公司 | Energy-saving and efficient reactor type thermal desorption system |
-
2021
- 2021-10-25 CN CN202111237764.9A patent/CN114011863A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103203355A (en) * | 2013-04-12 | 2013-07-17 | 江苏大地益源环境修复有限公司 | Ectopic thermal desorption treatment method of polluted soil |
| CN106140810A (en) * | 2015-04-02 | 2016-11-23 | 中环循(北京)环境技术中心 | A kind of complex biological treatment system repairing epipodium polycyclic aromatic hydrocarbon pollution |
| CN105689382A (en) * | 2016-01-26 | 2016-06-22 | 清华大学 | In-situ remediation system for organic contaminated soil |
| CN208341360U (en) * | 2018-05-02 | 2019-01-08 | 北京高能时代环境技术股份有限公司 | A kind of soil remediation thermal desorption heating device |
| CN110614266A (en) * | 2019-09-26 | 2019-12-27 | 中科鼎实环境工程有限公司 | Heap thermal desorption treatment system for repairing organic contaminated soil |
| CN111215440A (en) * | 2019-10-11 | 2020-06-02 | 广西博世科环保科技股份有限公司 | Organic contaminated soil in-situ alternate electric heating desorption system |
| CN111003792A (en) * | 2019-12-30 | 2020-04-14 | 浙江卓锦环保科技股份有限公司 | In-situ oxidation circulation extraction repair system and repair method for organic polluted underground water |
| CN213763426U (en) * | 2020-12-09 | 2021-07-23 | 北京建工环境修复股份有限公司 | Energy-saving and efficient reactor type thermal desorption system |
| CN112958612A (en) * | 2021-03-09 | 2021-06-15 | 上海格林曼环境技术有限公司 | In-situ thermal desorption method for repairing organic contaminated soil |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN202490819U (en) | In-situ remediation device for organic contaminated soil | |
| CN102580993A (en) | In-situ remediation technology for organic polluted soil | |
| CN104438315A (en) | In-situ chemical oxidation injection device for repairing polluted soil and underground water | |
| CN112081091B (en) | In-service industrial site pollution comprehensive management and control system and method | |
| CN110614266A (en) | Heap thermal desorption treatment system for repairing organic contaminated soil | |
| CN106734151A (en) | For the resistance heating original position thermal desorption repair system of VOCs contaminated sites | |
| CN111515237A (en) | Soil remediation device and method | |
| Sandhu et al. | Measures to mitigate direct flood risks at riverbank filtration sites with a focus on India | |
| CN114011863A (en) | Stack type thermal desorption technology | |
| Musche et al. | A field study on the construction of a flood-proof riverbank filtration well in India–Challenges and opportunities | |
| CN211218000U (en) | Heap thermal desorption treatment system for repairing organic contaminated soil | |
| Tokarz et al. | Improvement of the UCG process safety in a georeactor surroundings under emergency conditions | |
| CN208825190U (en) | A kind of contaminated soil in-situ heat repair system using distributed energy | |
| Xi et al. | Groundwater pollution and its risk in solid waste disposal site | |
| CN112302057A (en) | Construction method for integral separation of polluted land | |
| Wagner et al. | Using frozen barriers for containment of contaminants | |
| CN114226424B (en) | Method for dredging and disposing volatile organic compound contaminated soil | |
| CN114453405A (en) | Pile thermal desorption repair system and construction method for organic matter contaminated soil | |
| Barker¹ et al. | Containment barrier at pride park, Derby, England | |
| Ojoawo et al. | The system dynamics modeling method in application of geo-membranes as landfill liners | |
| CN113896387B (en) | Sludge purification and dehydration structure based on combination of thermal desorption technology and vacuum preloading technology and construction method thereof | |
| Bajno et al. | Structure and service safety of deep disposal landfills-case study | |
| CN212093710U (en) | Soil remediation device | |
| Cross | Landfill Covers 1 | |
| Soemantri | Storage tank secondary containment |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20220208 |
|
| RJ01 | Rejection of invention patent application after publication |